Yes, he's genetically inclined to put on mass. He had more muscle mass than most people his size that don't train, and is naturally a physically strong guy. He wasn't extremely obese when he had the surgery - nothing like the guys on "the biggest looser".
That said, authorities took him out of his house age 11 cause of domestic issues, he grew up in religious schools, and came out of the closet a few years ago. His mind is pretty fucked cause of all this mess, and eating was his way out (he's well aware of this, was in therapy for many years). He simply couldn't control it. He would actually eat mostly clean. It's just that when he had the cravings, he could eat non-stop. Apparently, if you have the capacity to eat like that, even rice in large amounts can get you pretty big (ask 'em Sumo wreslers).
I was against the surgery and tried to convince him otherwise for months on end, but he couldn't see any other way out of it. He's a very hard-working and dedicated guy, but he lost his war against food. =\
Anyhow - what approach should such a guy take? When he'll start training, what he'll practically need is getting the most nutritional value for the size of his meals. The amount of food he can take in is very limited per meal, but he can possibly eat some 6-7 small meals a day. BTW - I suppose Aerobics are out of the question, right?