If he actually did the right thing at some point, then possibly his anti-Trump comments are designed to save his reputation with his deep state buddies. If that's the case, it makes him look like a lying coward. If you look at his history with the bush admin, and especially his own actions regarding Ruby Ridge, it is clear that Barr is a deeply flawed criminal. Possibly the only reason he helped Trump was because Trump showed him the evidence of his past crimes (even crimes we don't know about) and gave him a chance to atone and avoid prosecution.