I think the success of that plan depends on what kind of mania he has if you confront him. He might not take it well if he is agitated or if he's feeling God like. He could even be violent if he's suffering from psychosis or a mixed episode.

It shouldn't be your place to call him out if he is treating patients in a compromised state, but I think you're a good person for considering his feelings and being willing to work with him. You're honoring what seems like a friendship that you've built over the years. I hope it works out that he is back to his normal self the next time you see him so that you don't have to risk rocking the boat. I'm sure you'll be able to feel it out and stay safe no matter what happens. Definitely keep us posted.