I disagree with the saying "Violence is never the answer." It's the only answer left if all other nonviolent ways to solve the problem have failed and the other part has more power than you, like, say, a bully.

Maybe Todd could have stood up for Anna in a different, nonviolent way. But his reaction still shows Sean that not all of the other kids agree with him or won't do anything to stop him. That's huge. Bullies rely on the complicit inaction of others to get away with their harassment.

If I were LW I'd be worried about possible retaliation against Anna or Todd, and make sure Todd knows about nonviolent ways to stand up for others to try first. But punishing him for standing up for the weak, just because it's inconvenient or shocking to the parents, it's not the lesson I'd like him to learn.