I don't believe for one minute Jesus was saying forgive them they not not what they do, for without Good reason or without cause, the only plausible explanation is the crowd believed Jesus was guilty and not innocent,
Why well pontas was told by his wife who in my opinion was given a dream by God to show Jesus was an innocent man, meaning not to condem him, but that was going to happen anyway mans own will was going to condem what they couldn't understand , because mans will is to please the crowd before they do God here, so pontas was made aware that he should believe, but Jesus knew he wouldn't anyhoo, but never the Less Jesus still convicted him. Because that's what the spirit does. So once again it point towards God providing the means before hand, because God had provided a dream before hand to his wife, the words of his wife was hes innocent.
Meaning pontas was made aware that if he condemned him then the crowds would believe he was not innocent, so now could you see the Pacific reason why Jesus may have said forgive them for they no what they do ?