It is a great finding in Irenaeus:
5. Others still there are who continue to redeem persons even up to the moment of death, by placing on their heads oil and water, or the pre-mentioned ointment with water, using at the same time the above-named invocations, that the persons referred to may become incapable of being seized or seen by the principalities and powers, and that their inner man may ascend on high in an invisible manner, as if their body were left among created things in this world, while their soul is sent forward to the Demiurge. And they instruct them, on their reaching the principalities and powers, to make use of these words: I am a son from the Father — the Father who had a pre-existence, and a son in Him who is pre-existent. I have come to behold all things, both those which belong to myself and others, although, strictly speaking, they do not belong to others, but to Achamoth, who is female in nature, and made these things for herself. For I derive being from Him who is pre-existent, and I come again to my own place whence I went forth. And they affirm that, by saying these things, he escapes from the powers.
https://www.newadvent.org/fathers/0103121.htm
This says us that the parody behind Barabbas has as primary intention to attack the Marcionite claim that the
"Jesus Son of Father" was crucified, as opposed to a Jewish Jesus
"called Christ" (point fixed by Couchoud/Stahl).
But this says us also that, in the original story (proto-Mark, without the Barabbas episode), Pilate is able to kill only the mere appearance of Jesus Son of Father: the mere carnal Jesus (
separationism).
Who was imprisoned in the human recipient is the spiritual Christ, who abandoned the mere man
by escaping Pilate, who therefore plays the role of the
Pylatis, the Archon gate-keeper.
The human recipient was confused with a
'prison', and it became, in the deliberate
parody, a Roman prison, the prison where the
criminal Barabbas has to be emprisoned.
And if you think that
PLT means
'fugitive' and not
'releaser', then here is the answer, too:
The last quote of Irenaeus above:
And they affirm that, by saying these things, he escapes from the powers.
...is translated in my version as:
And they affirm that, by saying these things, the powers escape.
