In my opinion, the nuance is whether the difference is truly because of gender or if gender is just something with a high correlation.
For example, if an average man says to me "give me your wallet or I'll beat you up", I'm likely to do it since I'm on the smaller side. If an average woman did that, I'd say no. So maybe it seems like sexism at first, but then I consider, if a woman threatened me who was the size and build and general risk of an average man, what would I do? I'd hand over my wallet.
> 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.