I was thinking this in my head, he tells the bully, hold on hold let me cut my fingernails real quick, I don't want to cut you. Spends 2 minutes cutting his fingernails neatly, while the bully is looking at him like wtf. Then BAM, punches him.

You did the right thing by standing up to your bully. If you don't they just do more and more and more. It is the school system and their "It is everyone's faults, the kids, the parents, the laws, but oh no we are not at fault, the school is never at fault."