While it seems improbable that “the rulers of this age” has a primary or exclusive reference to spiritual beings, this doesn’t rule out a composite view where the earthly representatives of the “spiritual authorities/rulers” are primary but understood as acting on behalf of supernatural beings who are depicted in apocalyptic literature as the real powers behind their human agents. While human agents might have crucified Jesus Christ because of some sort of blindness, their spiritual rulers knew exactly what they were doing. Again, one could argue that this is missing Paul’s point; that according to Paul, the blindness behind the crucifixion was something shared by both the spiritual rulers and their human agents.
So this is really more expected on Mythicism: the total ignorance by the ''rulers'' about the identity of Christ is more expected if there was no distinction at all between who would know more (the spiritual agents behind earthly agents) and who would know less (the earthly agents manipulated by who would know more) about the identity of the victim.
Said in other terms, if the ''rulers'' were only spiritual agents.
Nihil enim in speciem fallacius est quam prava religio. -Liv. xxxix. 16.
I've always felt that there was a sort of Platonic "on earth as it is in heaven" sort of thing going on in Christianity. The doings, beings, and actions within the heavenly realm being the ideal form(s) for the earthly mirror counterpart(s).