If proto-Mark is so boldly separationist - as I argue here - and he was betraying Paul insofar he was making great again the distance between the deity (the divine Christ) and the victim (the man Jesus), then there is surely a particular irony behind the sinedrites's opposition to the man Jesus (remember that the sinedrites didn't recognize that the man Jesus was possessed by the divine Christ: only the sinedrite Joseph of Arimathea recognized the separationist nature of Jesus and Christ).
The man Jesus was not the Christ of YHWH, and even more so, he was not the Christ of a higher god than the creator.
Therefore the sinedrites are moved to kill the man Jesus because they think that this man Jesus was posing as their Christ, hence posing as an earthly mirror of the creator. In marcionite terms, they hated the idea itself of a hologram for the deity.
We know that the Son of Man is Israel, the only “Man” who is made in the image of God (YHWH).
Therefore who hates the Son of Man hates paradoxically the mere earthly image of the creator.
Hence the irony of proto-Mark is that the sinedrites, hating the mere hologram, the mere man Jesus, the mere Son of Man, are really killing the same Israel (as people, a fact realized in 70 CE).
But the point of proto-Mark is that it is the same divine Christ - the Christ of a higher god, not of YHWH - to move the sinedrites to kill the Son of Man, the mere man Jesus, the hologram, i.e. Israel himself. And with him the Torah himself.
Mark 8
27 Jesus and his disciples went on to the villages around Caesarea Philippi. On the way he asked them, “Who do people say I am?”
28 They replied, “Some say John the Baptist; others say Elijah; and still others, one of the prophets.”
29 “But what about you?” he asked. “Who do you say I am?”
Peter answered, “You are the Messiah.”
30 Jesus warned them not to tell anyone about him.
31 He then began to teach them that the Son of Man must suffer many things and be rejected by the elders, the chief priests and the teachers of the law, and that he must be killed and after three days rise again. 32 He spoke plainly about this, and Peter took him aside and began to rebuke him.
33 But when Jesus turned and looked at his disciples, he rebuked Peter. “Get behind me, Satan!” he said. “You do not have in mind the concerns of God, but merely human concerns.”
28 They replied, “Some say John the Baptist; others say Elijah; and still others, one of the prophets.”
29 “But what about you?” he asked. “Who do you say I am?”
Peter answered, “You are the Messiah.”
30 Jesus warned them not to tell anyone about him.
31 He then began to teach them that the Son of Man must suffer many things and be rejected by the elders, the chief priests and the teachers of the law, and that he must be killed and after three days rise again. 32 He spoke plainly about this, and Peter took him aside and began to rebuke him.
33 But when Jesus turned and looked at his disciples, he rebuked Peter. “Get behind me, Satan!” he said. “You do not have in mind the concerns of God, but merely human concerns.”
The great sin of Peter in proto-Mark is surely to preach the strict identity between the man Jesus and the divine Christ.
As effect of this petrine sin, the same Israel (=the same man Jesus as distinct from the divine Christ) will suffer, etc. But in proto-Mark there is no prophecy of the resurrection of this Israel. Therefore the verse 31 is at least partially an interpolation.
Without that interpolated verse, Peter is rebuking Jesus because Jesus (better: his possessor, the Christ) is forbidding him to preach the strict identity between the man Jesus and the divine Christ. In this sense Peter is a Satan and therefore he doesn't realize that the Christ is the Messiah of an alien god.
The result is that the man Jesus, as Son of Man, will suffer in the place of the divine Christ.