Evidently in Ezek. ix, 2 he is a Secretary (or Recording Angel), and Zimmern (K.A.T. 404) does not hesitate to identify him as "manifestly the Babylonian Planet- and Secretary-God Nabu," akin to the Greek Hermes, whence may be explained very naturally the term "young man" used by Mark. It seems, then, that we are dealing with a technical expression for a celestial personage
(Ecce Deus, p. 112)
This would explain why the Docetists could read completely undisturbed all the Passion stories of the various gospels. It was sufficient, for them, to point out the escape of the naked young (i.e. Jesus) to elude in advance any catholicizing insistence that Jesus "really" suffered.
The colossal irony would be that the pious women saw Jesus in the tomb, masked as the young in white robe, hence the 'risen' Jesus that the 12 would have seen in Galilee would be just as fictitious (a mere double) as the Jesus who was crucified.
If the young naked was so heretical in his docetic function, then why did the catholics preserve him in all the gospels?
The reason is that the Catholics felt themselves reassured about the christological implications of the naked young, since the Barabbas episode was designed to confirm again and again the readers about the orthodox identity of the real victim: he was the Jesus called Christ, not a marcionite and docetic Jesus Son of Father. How can you doubt about it?