Just leave him alone and may posterity forget who and what he became after Vietnam.
In defense of McCain, and that is not easy, I think he was mentally broken while imprisoned. I think he never recovered from his treatment at the hands of North Vietnam.
ps
My brother worked on Phantoms as an electronics tech in Vietnam. After the war he meet a few of the pilots on whose planes he worked. Pilots that were shot down and captured. He said some were really messed up mentally.
Perhaps he was and is broken. In which case he is unfit to serve as a United States senator. But since he has taken that role, he will be accountable for his actions, his votes and his comments.
McCain was a worthless ass long before Vietnam.