not at all.........bad form maybe, but sometimes bullies need a taste of their own medicine to actually get the message.
my DD1 was bullied in primary school, and the school was useless.
DD1, after having 2 pairs of glasses broken by this girl hitting her so hard around the face they flew off and smashed, ended up chasing said girl and pulling her trousers down in front of a lot of the school when on the school field (in fact, said girl was on the monkey bars). humiliated her so much, she never acted like that again, towards my DD, nor anyone else ASAIK. (didn;t stop her being a gobby mare, but not physical again).
I don;t normally recommend violence, but self-defence or retaliation in keeping with the offence, I have to say, it is needed.
how does your son feel.........I would bet the confidence boost is huge