Since he avoided punishment for the Keating Five deal McCain has considered himself untouchable. Anything that doesn't remove him from office only emboldens him. Trump's wisest strategy is to just shut up and let him die in God's own time.
I agree. Trump needs McCain more than McCain needs Trump. McCain will die enacting his revenge on Trump and there’s not much Trump can do about it except tweet.
McCains NVA prison story is a study in cooperation with the enemy