Penny,
Self defense isn't just important in high school. When you are a guy you pretty much deal with it your whole life. I know you don't want to teach violence, but there are just some people that don't understand anything else. Those kind of folks aren't restrained by any sense of right and wrong. They are only limited by fear. If they aren't afraid of getting their teeth knocked in, they will do/take whatever they want from your boy. He will be a man someday. And someday his wife and children will be looking to him for protection from those kinds of folks. If he is ever going to have anything, he needs to know how to defend it.
It is difficult for you to understand. Men and women just live in different worlds and have to deal with different things.
Can I ask you a personal question? Is his dad around?
Another thought on training. Apparantly this is an immediate and pressing problem. Most martial arts training will take a little while to be effective. You might want to consider the types of methods that give you the most effectiveness with the least amount of training time.
What is the situation exactly? Maybe some folks around here can give you more specific ideas for how he could handle this.