I think we all want to stand up and be tough. But just from a safety standpoint, probably best to just take the child and move out of the scene. If you start pushing and getting involved, now your safety as well as the child's safety in jeopardy imo.
I almost got into a fight at a nightclub bc a scuffle in front of us ended up giving my gf a bloody nose. But I had to attend to her first and get her to the washroom and make sure everything was good before taking out my anger. And by that time, my gf calmed me down and said there was no point in getting involved since it was an accident and if I get into a fight she might get hurt again and we might not end up having fun after getting kicked out. She kept me in check and even though I still fantasize about beating the poop out of them, it was probably the right thing to not get involved. And we ended up having a good time afterwards.