What would you have done?

We are at the local McDonald's, Alexis and her friend are playing.... the girls come over to get a drink, and another little girl starts to cry hysterically another little boy has hit her, the dad of the little boy pulls him aside and does the standard we dont hit other people and puts the child in a time out, the little girls mom glares at him grabs up the daughter and stomps away ,the dad says again ma am I'm sorry. I feel bad for the dad we all have had moments that our children act a fool so I laugh and say well hes for certain all boy. Dad gives me a grateful look and all is well. Not more than 5 min later this same boy pushes Alexis friend and they both come running I ask them both are ya'll ok? yes we are, ok then go play..... The next thing I see is this same boy biting Alexis ,yes you read correctly bites her!!!! Whooooaaa ok this is a game I DO NOT PLAY!!!!! She screams I jump and run to her like an Olympian hurdle person (you know leaping small children in a single bound type thing) This bite has broke the skin and is bleeding. I run for ice, the dad swoops up the boy and starts to scream and yell and beat the child, he takes the child to the truck throws him in the car seat beating him the whole time. He comes back says to us Im sorry little girl are you all right? Well hell no shes not all right and Im so mad I wanna kick his sorry butt clear to Burger King. But with the way hes beating this little boy I sure don't wanna piss him off anymore. They leave we gather our stuff up and head to the pediatrician, we are on antibiotics and all is well. I got his license plate number and make and model of vehicle called the police and pressed charges and told the police officer how badly this man was beating his child. Did I do the right thing? or did I make a bad situation worse??? you tell me