How can you justify that? What if he decides, that when he reaches 18, he wants to join the armed forces to serve his country? Are you going to cut off all ties with him? I'm going to a university, and serving in the armed forces. If you have the motivation, you can do most anything. I don't think you should suppress your kid's desire like that. Especially if it is patriotic.
Now joining an art school, I completely think is a waste of time. But that's a topic for another day.