So the child calling him this name is actually bullying him as well, with physical violence. The school definitely needs to be involved - bullying's intolerable, the name-calling is but one part of it.
I remember I was working at the council in 1983 when I first heard this word 'racist'. One of the women walked in the office and used it and we all looked at each other wondering what it meant. She explained it and we just rolled our eyes and wondered what planet she was on.
Now it seems this horrible word has become part of the vocabulary and psyche. It's a very unpleasant word and it becomes apparent it's the more unpleasant people who use it. These threads are horrible.
I think the pikey comment is the least of his problems. The school should already be taking action. Name calling is something kids have to deal with, in reason, but not having their possessions deliberately damaged and certainly not suffering injury caused in malice!
Good luck, it's horrible knowing this stuff is happening and that you can't be there to help them.