My Shaye loves being rolled over for bellly rubs, but really prefers lying on her side for them, when she puts her paws over her face while it's going on. We've had her since she was 11 weeks and mauled her every way possible so you can really do anything with her and she's fine with it. On the other hand, Gemma didn't come to us until she was 14 months, and used to be if you touched her feet or tail or tried to maneuver her out of any position she was in, she would "grin" at us, that toothy warning sign. She's now 4 yrs 4 months, and we can touch anything without a problem, but rolling her onto her back, even for belly rubs, makes her whine, and she sort of doesn't breathe right. We cannot pick her up, she squirms and fights it, and she's a mix, 35 pounds, so we don't try that often. Just give your boy his space, gently try to pick him up and quit when he resists, rub his belly any way he will let you, and eventually, he'll calm down for you probably.