Imo what is going on is, he is not getting enough mins to earn his money in addition to the known locker room drama
If he is going to be paid 6 million a year, he wants to play to win a ring. Only way i see him want to play as a celtic is bc we have a good locker room culture and he can get a chance to play some more min
But again likely his first choice is to go to a team that has a chance to win, like the clippers