It's a funny tale, no doubt. And bad plan on the part of the instructor to not pay more attention as people are hitting him. But I have to say, your 5 year old is not ready to start training. If his goal to hurt people is so great that he breaks the ground rules of an exercise, he shouldn't be in class. At the very least, I hope the instructor made him do more pushups than he count. I'd have ejected him from class. But then again, I refuse to teach kids.