Just because we are now six years removed from his disastrous presidency doesn't mean his gag order is now lifted.
The entire Republican Party basically has no room to criticize anyone else's foreign policy for a generation. They lost their credibility with Dubya's Iraq Adventure just as LBJ threw away the Democrats' credibility by going into Vietnam.
These weren't public comments.
So he should get a pass because he's too ashamed to say such nonsense in public? While I think it goes too far to call him a war criminal, he'll likely go down as the worst president of the 21st century, and he's certainly the worst since Wilson.