No he isn’t
A true mentally ill person would’ve stood on business and doubled down
Based on what? He's bipolar and refuses to take medication, which means he is in a constant state of psychosis. You have no idea how he came to this conclusion so making a definitive statement like that makes no sense. Maybe he took his medication this week. Maybe he reached a bottomless pit so vast that he realized, even without medication, that the end is near. My cousin is bipolar and sometimes she knows she is making a bad decision but decides she needs to "clear her head" until she reaches a point where she willingly takes her medication. Other times she gets arrested or institutionalized. She's been talked out of jumping off large buildings while in a psychosis state, sometimes in the most random of ways. One time she was told if she jumped she wouldn't get to have her favorite dessert (German chocolate cake) that evening, and that (literally) convinced her to come off the ledge. Long story short if you are expecting some consistently or logic from his behavior you don't understand the situation.
He might turn around next week and say Hitler was right, or that he was forced to make this statement. Based on his previous actions and the fact that he's in the middle of an album rollout, I expect more fukkery and suspect this is a part of it.