B.C.
You feel a need to be there when the school tells the kids involved to keep their hands to themselves?
Sorry but it is over reacting.
What you tell your son is that everyone really should keep their hands (and feet and all their body parts) to themselves and he did do the right thing about telling the teacher about it and you are proud of him for doing the right thing.
If this other boy is always trying to force other kids to do anything it's probably a good idea for your kid to spend more time with other kids - and I'd tell the teacher that.