It seems like he's not really at the maturity level to be out on his own. Even so, people have to be allowed to make their own mistakes. It's how we learn who we are, and how we begin to grow up.

Btw, do you realize that you sound kind of disdainful when you talk about him...? You cant really be friends AND a "mentor/ role model". True friends, whatever their situation/ age/ degree, deal with each other on equal levels. Example: My husband has a Masters degree, but most of our friends never even went to college. Yet he never sets himself up as better than anyone else- even though many of our friends are way younger than us.