Board Thread:Speculation House/@comment-16502426-20140525052751/@comment-70.94.227.99-20140528180248

You also need to think that Ozpin was surprised that Ruby could use Cresent Rose, and while slightly awed, he was basically saying, "While you're too young to go to Beacon, why don't you anyway?". Upon seeing Ruby's mad skills, he basically recruited her. It could have been part of a bigger plan, and he wasn't afraid that a child would possibly get hurt.

After all, Ruby couldn't have done it all by herself, because Glynda had to help, so he knew that wasn't afraid to let others lead, of help. Thus, he made her leader of team RWBY because he knew she could handle herself in any situation no matter how big. He and GYlnda also knew Jaune had nothing much weapon-wise, and yet, when he was asking an important question, they let him fly, leaving him to either die, or be rescued by someone (A.K.A  Phyrra).

So he is not going to let something trivial like age or nothing to help the student get in the way. It's every man (or woman) for themself until battle or death claims you.