He needs a bit of work to make him marketable. Singing live he's all over the place whenever he 'releases the nitro', and he isn't very good at promotional interviews, giving short or noncommittal answers punctuated by giggles. He's going to be a tough one to market when he can barely promote himself.
The biggest 'red flag' though is the way he's already refused to do things because of his religious morality (example, the group song which referenced drinking alcohol). I adored Marcus Canty from last year's X Factor USA, he's a rare thing these days; a young black guy with an authentic R&B singing voice who doesn't rap like the others all feel they 'gangsta' should, and he is also a very religious guy. But that didn't stop him from being a sexy dancer, sliding underneath some girl singers' dresses in an XF dance routine, and singing about contemporary themes in his music post XF. Will Jahmene 'tart out' a little to make himself commercial?
If he's going to be all puritanical about things he may end up limiting himself into making an album of gospel/christian music and politely safe old skool soul covers, and I can't see that selling well. But if he was prepared to be more mainstream, taught to control his runs, and coached in interview techniques, he is perhaps the only act this year with any obvious chance of breaking through in America.