Assuming Justin was one of the first people to read the first gospel, then the question is raised: was a legend about a Christian Pilate already diffused about the same time?
A reason to think so is the embarrassment behind Justin's claim that the Acts of Pilate can be found in the Roman archives: evidently someone was questioning the historicity of Jesus' crucifixion.
A reason against is that Justin follows the Lukan interpretation of Psalm 2:1–2:
“Why do the gentiles conspire, and the people plot in vain? The kings of the earth set themselves, and the rulers take counsel together, against the Lord and his anointed.”
...and he offers this interpretation of the Psalmist’s words:
“[David] testifies of the conspiracy which was formed against Christ by Herod the King of the Jews, and the Jews themselves, and Pilate, who was your procurator among them, with his soldiers.”
https://www.newadvent.org/fathers/0126.htm
This indicates that he viewed Pilate as a co-conspirator with Herod and the Jews in the death of Jesus.
Hence, I wonder if the two thieves originally were not found in the first gospel. They were added to replace Pilate and Herod as the two true evildoers conspiring against Jesus.
In conclusion, I am inclined to think that it is not a coincidence that the first extra-Gospel Christian writer to talk about Pilate is also the same person who felt the need of mentioning fantomatic Acts of Pilate.
Obviously I am excluding a priori the forged Testimonium Taciteum as irrilevant to the discussion.