Should I press charge against a men yelled at my 8 years old nephew?

My nephew is a 8 years old Chinese boy and spending the summer with me. When I picked him up from camp yesterday, a man was yelling at him and pointing his finger at him. The man accused that my nephew is a lier, and tried to choke his daughter. I told the man that my nephew is not a lier and certainly not a killer. The man continued yelling at both of us and called me a bitch. After talking to the man's daughter, it turns out that my nephew placed his hands on the girls shoulder, not at all around her neck, during a game which happened 2 days prior. Nothing serious happened according to the camp director. Under my instruction, my nephew apologized to the girl for being rough. I also requested the man to apologize. The man did what he was told, but he was not sincere. He told my nephew that he need to stop being mean to others during his apology, which I interrupted. The camp director and a couple of others witnessed most of the incident.