I would not say you are acting sexist in your analogy. If we take average male vs average female, yes there is a large strength disparity and your response seems very justified. It is clear that your response is more linked to the danger that you're in. I would contrast this from my analogy (black person walking towards you and crossing the street) because there's not a good justification for thinking that the black person is more likely to mug you than if a white person was walking towards you (there's no justification for increased danger). I'd argue that the priors are different in these situations (I'm sure there are people that would disagree and call your response sexist, but I will say that my thesis is about not binning people to easy little boxes. "us vs them". That responses need to be thoughtful and tempered).

> I understand the meanings of words like "sexist" and "racist" are changing and subject to opinion.

Also on this point, I think this kind of "words having different meanings to different people" is far more common than people realize and requisites more care in how we interpret others' statements. I think this is obviously true for any "ism" (sexism, racism, capitalism, socialism, etc). Pinning a definition to strictly our own interpretation ends up being naive and often leads to fighting because we have basic breakdowns in communication. We can't agree even if philosophically we agree. It should be the other way around, meaning triumphing over diction. Diction over meaning is just looking for a fight.