It is generally rude in Western cultures to assume that someone is being controlled by something outside of their own volition, ie, to imply that they have less than full agency. This is most likely borne out of the Enlightenment era and its emphasis on the ideal of individuals carving out their own destinies as the highest moral pursuit.

I personally think we will have to contend with the present and future of neuroscience research that investigates the distinction between which wills are truly free and which are conditioned on past experiences.

All that to say, however, that 'sexist is as sexist does'. If such language as in GP is used to denigrate the position of the woman in this disagreement by casting her as a nuisance to be managed externally, then that is sexist, because she is no longer afforded a voice in the discussion but is instead reduced to an object to be manipulated, the primary reason for this being her gender.

But I wouldn't recommend trying to close an argument by saying "Hey honey, I think you've been brainwashed by patriarchy. Don't you think we should try to challenge established hygiene and gender norms with this dirty glass standing as act of protest?"

You can point out / criticize trends and large-scale causes without stereotyping people or turning a trend into inescapable destiny.

In general by explaining behavior by societal trends you're removing agency. To say women are making their choices because of the way they're influenced is to say women cannot make independent choices without being swayed by outside influences. It's kind of a paradoxical thing

What human being on the planet can make choices without being swayed by outside influences?