Waiting for the whole story. Wonder if he had discussed the problem with the school’s principal, with the bus driver? Often, these days, you can do all the right things and get no results!
I’m afraid if I were in his shoes, I might have done something similar if official channels hadn’t worked. Then, there is always, drive your daughter to school and pick her up while bullies are being dealt with properly, or keep her home.
There are new rules in place to protect people, especially children from being bullied. Might as well use all the P.C. stuff when you can!
I can understand why he did it.