I agree with much of what you've said: Certainly, the problem is not the behaviour of the children, (because it is not abnormal for children that age) - the problem is the behaviour of the adults. I am of the opinion that the woman was completely unreasonable and antagonistic, and even provocative. However, the man did cross a line when he became physical (when, up to that point, he had been the more reasonable and calmer of the two), and I believe that this is what distinguishes him (and hence the sanction against him) from the woman.