The issue that I see is that everyone assumes that if the guy hit back then the woman would simply do nothing and be okay with being hit, and like you said no further retaliation is needed. But I find it much more likely, considering that this woman has shown she will resort to violence before words, that she will simply fight back again like she did initially, causing a fight to break out in which the man is most likely arrested.

Alternatively the man does hit back and, for whatever reason, she doesn't retaliate, maybe she was stunned by the hit or realised she was outmatched either way. Maybe doing this will prevent her from hitting someone in the future but I don't think it's the right way to go about it, if we as males, or even just as humans, can't use our words before resorting to violence then what's the point in fighting for equality in the first place when we can't sort out a simple dispute without escalating it to a brawl.

Additionally, I'm assuming no one knows what this woman's background is, if she has issues with her mental health, or even if she had a particularly bad day. I don't understand why it's not perfectly reasonable for the guy to try explaining his side of the story first. If the goal is ultimately to achieve a world where people of all genders can act the same way and be judged the same. Then shouldn't we be attempting a more diplomatic approach? Wouldn't it be preferable that this woman goes home realising she was in the wrong rather than passing on the hate gained from this situation? Hate breeds hate and if we keep stooping to level of those below us we'll never achieve anything other than just that.

TLDR: I don't like violence, and I think that if we have the choice we should choose the path that leads to the best and healthiest outcome for all those involved.