The white guy went after the short guy who was leaving with his crying daughter. The short guy was no longer in a scuffle. When you are restrained like that would you not start throwing punches to release the grip. The whit guy has the height advantage. The white guy probably had been convicted before for fighting and thought this time he would not throw any punches but still continue to assault him not knowing the meaning of assault.
Provoking and taunting someone to throw punches is well known habit of bullies. Pushing, pulling and shoving the victim is the way bullies provoke the victims.
If I was the passerby, I would have walloped the white guy for doing this to the father when the little girl was crying.
I have no idea what the short guy did but would you do this when the girl is crying. I bet the white guy would not have taken on someone who was taller or better built.