I would have done the same thing.
One of my biggest pet peeves in the world is parents who do not discipline their children. I do not have kids yet, but I used to be a full time live in nanny for some very un-disciplined kids and I think it is awful! UGHHHH!!!! What a rude woman to not repremand her child.... and how awful that the child would even behave that way. YUCK YUCK YUCK!!! What a little devil--- you are right!
I am glad your baby is ok! I hope he bites that little brat next time he comes around