I would encourage it if I were you.
Actually, I think our higher-level education system would be a lot better if we would all take about a year or two off before going to college to be away from the parents while not having to deal with the responsibility of education.
Also, its just highschool. For most kids its not that hard. A lot of it depends on when he wants to go to college. I assume that he wants to go after this summer. If his grades slip a little, but he has no plans to get into an ultra-competitive college, then what does it matter?
Oh yeah, he’ll be back for food. That’s a given, especially if you are living in the same town (I gather that is true). I am 23 and I still can’t feed myself properly. If my parents lived in the same town as me, I’d eat supper at my parents house almost every night. Clothes aren’t a problem. I’ve got that covered by now 
Again, a lot of it depends on how rebellious he is too, and how much he feels confined. A lot of parents are really protective, and thus, when their kids get the freedom of college, they go nuts. My parents were not so protective, so college wasn’t so crazy, but of course my town wasn’t really fun either, so I kind of went crazy (in a responsible way, if that makes sense
)
But really, I wish things were set up to where people would take a year or two off to work a while and simply get used to living by their own rules before starting college. Basically it should be as fun as college, but with no studying, but rather working. Too many kids jump straight into a high-pressure career path right after college, and basically miss out on a very good chance at adding to life experiences and building character. Social skills take practice, and you can really build on them a lot by having lots of freedom to just hang out and do whatever with minimal restraints (outside of a job, or course).
But yeah, I think its a great idea, and if I were you, I would encourage him to not rush into college. He’ll really appreciate you and respect you too, I think. I have a lot of respect for my parents, because they appreciate how I’ve grown through times like these, even though they offered some support.
If he screws up, he’s young. As long as there’s no legal troubles then I think it will probably be okay.