That's not what I asked. Thanks for waisting our time. It's a terrible choice. He'll be a henchman for corrupt politicians no matter who wins the elections.
Merits aside, there is not much you can do. Even if you could, he could sign up at 18 anyways and you'd probably put a serious rift between him and yourself. Sucks that it's against your wishes, but might be best to accept the inevitable and try and be supportive.