Well I know a couple of people that get good results at A level ( A*A*A*a ) results on hard work alone, they're not very clever, even by their own admission. I also know people who are clever and haven't done very well at all, (CBB). Though not being able to work hard, is just as bad as being stupid, it's a genetic fault in my opinion. You can tell when people are clever or not when you talk to them for a while, clever people tend to come up with original ideas, and innovative propositions, free thinking and imagination. That has absolutely nothing to do with grades.
Clever + Hardwork = A*A*A*
Not Clever + Hardwork = A*A*A*
I got good grades, I scored an A* in A level maths amongst other good grades. Now hypothetically, within the realms of human achievement, if somebody scores A*A*A* it isn't very impressive is it? Don't be so flippant about people. Now if he can't work hard, then that will shine through to other areas of his life, that's a different matter. And concerning if Academia is for him or not? perhaps it isn't but that doesn't mean he can't be infinitely more successful than someone who suits academia. For example, I know builders who left school at 15, and they are profoundly more successful/wealthy than a great many number of people I know who went to top Universities...