Understand where your coming fom completely, my daughter who is 14, has always been the target for bullies, it all started because she had speech problems when she was younger, and was noticed to be "different" at school, unfortunately this has followed her in her school life even though she is fine now, and she gets started on in school nown again, I have told her to just punch fu*k out of them as she is more than capable, but she just wont do it, so I find that im always intervening, just the other day she went out of the house and she come running back terrified, as some girls were following here calling her a scumbag...out I went and confronted them...yes they were scared but I dont think it works long term....I agree with your husband, and just wish my daughter would just get some guts and go for it .....everyday I worry about my daughter coming home from school, and am thinking of enrolling her in self defense classes, she used to go karate but was scared of the teacher!
Not much of an answer here, but just wanted you to know that talking to teachers and intervening yourself works for a short while, but not long term...your son really needs to give some back....its such a shame that we have to teach our kids to fight!