If so the issue is that Mark 10:24 in Clement's version is talking about trusting in riches i.e. avarice greed while the passage in Matthew is talking about being rich having lots of money. The Matthew passage provides little foothold for Clement's exegesis.
But is Matthew more specific or more problematic for that interpretation? Even where Clement mentions Matthew's 'additions' Clement sees them as compatible with his exegesis. So QDS 17:
προσέθηκεν ὁ Ματθαῖος· "μακάριοι οἱ πτωχοί·"
The only meaning here is that Matthew 'added' a partial reference to what is for us Matthew 5:3. But Luke 6:20 has Jesus saying Μακάριοι οἱ πτωχοί while Matt 5:3 adds (or Luke omits) τῶ πνεύματι. The first point is of course Matthew 'adds' μακάριοι οἱ πτωχοί to what exactly? Not Luke. So what exactly? It has to be Mark.
Mark is the immediate context. Matthew accordingly 'adds' to Mark that 'blessed are the poor in spirit.' Clement is able to make the addition in Matthew 'work' with his mystery exegesis here and could certainly have done the same with Matthew 19:23. This is the advantage of allegorists they can blur the distinction between anything and everything. So there has to be ANOTHER REASON Clement starts with Mark.
Staehlin emphasizes that this isn't a passing interest in Matthew 5:3 or the equivalent (the Marcionite gospel also had this reading). He says the interest shows up - QDS 16 § 3 (p.170, l.12) "This is he who is blessed by the Lord, and cared poor in spirit, a meet heir of the kingdom of heaven, not one who could not live rich." BP1, 17 § 5 (p.170, l.33) (what we just cited above) and BP1, 19 § 2 (p.172, l.2) BP1 "Let the former be possessed by the carnal poor, who are destitute of the latter. But thou, by receiving instead spiritual wealth, shalt have now treasure in the heavens." In other words - and this is critical - Clement begins by citing from the Gospel of Mark choosing it over Matthew for some reason. He is prompted by a version of the parable of the camel through the eye of the needle which as we know Celsus says betrays knowledge of Plato. In order to combat the communist interpretation of this passage Clement brings forward the long citation of Mark even though his citation of the parable takes on the Matthean form ('kingdom of heaven' versus 'kingdom of God'). After this long citation of Mark Clement proceeds to cite another gospel
which is not the same as the Mark text cited in chapter 4. This text holds all the keys to the mystery rite used in his community namely that one must strip naked and receive a divine soul through baptism.
Worth pointing out that Tertullian/Irenaeus's exegesis of Luke 6:20 assumes that the Marcionite gospel had 'poor in spirit':
To him, for whom in every stage of lowliness there is provided so much of the Creator's compassionate regard, shall be given that kingdom also which is promised by Christ, to whose merciful compassion belong, and for a great while have belonged, those to whom the promise is made. For even if you suppose that the promises of the Creator were earthly, but that Christ's are heavenly, it is quite clear that heaven has been as yet the property of no other God whatever, than Him who owns the earth also; quite clear that the Creator has given even the lesser promises (of earthly blessing), in order that I may more readily believe Him concerning His greater promises (of heavenly blessings) also, than (Marcion's god), who has never given proof of his liberality by any preceding bestowal of minor blessings.
Also that Origen in his response to Celsus makes much the same argument - namely that "blessed are the poor in spirit" helps explain the parable of the camel through the eye of the needle:
In the next place, with regard to the declaration of Jesus against rich men, when He said, It is easier for a camel to go through the eye of a needle, than for a rich man to enter into the kingdom of God, Celsus alleges that this saying manifestly proceeded from Plato, and that Jesus perverted the words of the philosopher, which were, that it was impossible to be distinguished for goodness, and at the same time for riches. Now who is there that is capable of giving even moderate attention to affairs — not merely among the believers on Jesus, but among the rest of mankind— that would not laugh at Celsus, on hearing that Jesus, who was born and brought up among the Jews, and was supposed to be the son of Joseph the carpenter, and who had not studied literature — not merely that of the Greeks, but not even that of the Hebrews — as the truth-loving Scriptures testify regarding Him, had read Plato, and being pleased with the opinion he expressed regarding rich men, to the effect that it was impossible to be distinguished for goodness and riches at the same time, had perverted this, and changed it into, It is easier for a camel to go through the eye of a needle, than for a rich man to enter into the kingdom of God! Now, if Celsus had not perused the Gospels in a spirit of hatred and dislike, but had been imbued with a love of truth, he would have turned his attention to the point why a camel — that one of animals which, as regards its physical structure, is crooked — was chosen as an object of comparison with a rich man, and what signification the narrow eye of a needle had for him who saw that strait and narrow was the way that leads unto life; and to this point also, that this animal. according to the law, is described as unclean, having one element of acceptability, viz. that it ruminates, but one of condemnation, viz., that it does not divide the hoof. He would have inquired, moreover, how often the camel was adduced as an object of comparison in the sacred Scriptures, and in reference to what objects, that he might thus ascertain the meaning of the Logos concerning the rich men. Nor would he have left without examination the fact that the poor are termed blessed by Jesus, while the rich are designated as miserable; and whether these words refer to the rich and poor who are visible to the senses, or whether there is any kind of poverty known to the Logos which is to be deemed altogether blessed, and any rich man who is to be wholly condemned. For even a common individual would not thus indiscriminately have praised the poor, many of whom lead most wicked lives. But on this point we have said enough.
It should be noted that it is Origen who says that Jesus was too Jewish to have read Plato. Celsus could have countered (as I would have) that Mark when adding his mystical bits to the original anecdotes of Peter could have also incorporated Plato into his 'secret gospel.' It is also tempting to wonder whether Origen was reworking an original response to Celsus written by Clement or whether QDS was a response to points raised by Celsus about the correct reading of the gospels. This passage in QDS is reminiscent of arguments made by Celsus:
What then was it which persuaded him to flight, and made him depart from the Master, from the entreaty, the hope, the life, previously pursued with ardour? -- "Sell thy possessions." And what is this? He does not, as some conceive off-hand, bid him throw away the substance he possessed, and abandon his property; but bids him banish from his soul his notions about wealth, his excitement and morbid feeling about it, the anxieties, which are the thorns of existence, which choke the seed of life. For it is no great thing or desirable to be destitute of wealth, if without a special object, -- not except on account of life. For thus those who have nothing at all, but are destitute, and beggars for their daily bread, the poor dispersed on the streets, who know not God and God's righteousness, simply on account of their extreme want and destitution of subsistence, and lack even of the smallest things, were most blessed and most dear to God, and sole possessors of everlasting life.
Nor was the renunciation of wealth and the bestowment of it on the poor or needy a new thing; for many did so before the Saviour's advent, -- some because of the leisure (thereby obtained) for learning, and on account of a dead wisdom; and others for empty fame and vainglory, as the Anaxagorases, the Democriti, and the Crateses.
Why then command as new, as divine, as alone life-giving, what did not save those of former days? And what peculiar thing is it that the new creature s the Son of God intimates and teaches? It is not the outward act which others have done, but something else indicated by it, greater, more godlike, more perfect, the stripping off of the passions from the soul itself and from the disposition, and the cutting up by the roots and casting out of what is alien to the mind. [QDS 11, 12]
Celsus makes this point over and over again in his work. This is his point in the passage above. And this sort of argument repeats over and over again in the True Account. But it is even more interesting that Democritus and Crates appear side by side and in the same order to Clement's comments about the poor:
In the person of the Jew, Celsus continues to find fault with Jesus, alleging that he did not show himself to be pure from all evil (ὡς μὴ δείξαντι ἑαυτὸν πάντων δὴ κακῶν καθαρεύοντα). Let Celsus state from what evil our Lord did not, show Himself to be pure (οὐκ ἔδειξεν ἑαυτὸν
καθαρεύοντα ὁ Ἰησοῦς). If he means that, He was not pure (μὴ κεκαθαρευκέναι) from what is properly termed evil, let him clearly prove the existence of any wicked work in Him. But if he deems poverty (πενίαν) and the cross to be evils, and conspiracy on the part of wicked men, then it is clear that he would say that evil had happened also to Socrates, who was unable to show himself pure from evils. And how great also the other band of poor men is among the Greeks, who have given themselves to philosophical pursuits, and have voluntarily accepted a life of poverty, is known to many among the Greeks from what is recorded of Democritus, who allowed his property to become pasture for sheep; and of Crates, who obtained his freedom by bestowing upon the Thebans the price received for the sale of his possessions. Nay, even Diogenes himself, from excessive poverty, came to live in a tub; and yet, in the opinion of no one possessed of moderate understanding, was Diogenes on that account considered to be in an evil (sinful) condition. [2.41]
When Clement says in QDS 11 and 12 that the 'poverty schtick' has been 'done before' by pagan philosophers and that Jesus is offering something new it fits within the continuum of arguments made by Celsus. I even go so far as to wonder whether Origen rewrote many of Clement's works - the Stromata, the First Principles (mentioned in QDS as περὶ ἀρχῶν καὶ θεολογίας [On first principles and Theology] (cf. Giulea 2009:187-213; Osborn 1994:1-24) and referenced in Stromateis 3.13.1, 21.2, 5.140.2) albeit explicitly using the new orthodox canon developed around the four gospels.