It would seem to me that a man would have to actually think in that situation. If the woman attacking him is much smaller than he, not very athletic, and not attacking in a trained manner, just flailing, there are ways to ensure he does not get hurt without hurting her in the process. If, however, the woman is an actual danger to the man, larger than he or perhaps been training in how to fight for a few years while the man has not, it's a different kettle of fish. In normal circumstances, no, absolutely a man should not hit a woman, but today's women are not all the shrinking violets of a few generations back. And all bets are off if she has a weapon. Then it's stop the fight before someone really gets hurt.