I really, really hope that when Grandma tells Joey's parents, they take appropriate action. I can't imagine a parent letting another parent yell at their kid over anything, even if they "grumble" themselves, but I worry that they won't take proactive steps to make sure the other boy doesn't continue his father's work, or that if the boy "tells" on Joey, the teachers respond appropriately.

As for what to do about the man being a principal, man, that's tough. I would want to take more action to protect other children from him, but I'm not sure what or what channels.