This is difficult i suppose because technically he's an adult but if he's having his own issues he'll need as much support from his family as they can offer. I think it needs to be offered at a distance though - if he's not always able to function adequately maybe supported housing could be looked into or a therapeutic community? I'm not in the US so i understand those sorts of things can be very costly but maybe his health provider would have some advice on the issue? If you think that's a stretch too far maybe an ultimatum of sorts needs to be delivered once he's in a better frame of mind. I think if the focus is put on the fact that it would ultimately be the best for him, he might be more open to the idea. I mean, i don't know of many people in that age category who don't want a life of their own. And maybe that's what's frustrating him - if the counselling wasn't very good or he wasn't feeling heard by his last doctor could a new one be found? I think there are options in situations like these but flexibility needs to be in supply and sadly when tensions are high this isn't easy. I wish you luck in finding a solution.