This isn't college, this is highschool. If he is put into a fighting situation, then the cost of not-fighting will be having to fight EVERY DAY. It is much less damaging to, with a witness ready to testify to your innocence and the playing field at least partly under your control, simply lay one person out flat on the floor now and go more than a little bit psychotic on him to make him look like an absolute fool TODAY, than it would be to have to fend off a surprise attack (being accused of being the violent aggressor and attacking unprovoked each and every time) on Monday, and Wednesday, and Thursday, and next Monday, and Tuesday, and...

I agree with keeping the guard up, but thought it was self-evident.