I would like to get this straight: According to you 
1)the father had no right to approach the mother and request that she take action against her 8 year old son for slapping his 4 year old daughter in the face.
2) It was totally acceptable for the woman the to tell the guy to "fuck off" when politely asked to take action against bullying.
3) Bullying of children is acceptable "what happened in the play area, although in dispute, is a straw man"
4) Defending a child from being assaulted is misogynistic and racist.

Clearly your not a parent, as a father I can tell you that if a child twice my child's age attacked my child and the child's mother told me to fuck off I would bitch slap her no matter what her race, and if my son hit a girl in the face and the parent confronted me, my son would be on the receiving end of my anger not the parent.
Had the mother done the right thing and taken her son to task for the bullying this matter would never have occurred thus SHE is the guilty one.