The issue is not just one of violent men, but also very much about one of the privacy and dignity of one's sex. We know that many men are motivated to transition by AGP ( read Janice Turner's interview a few days ago with Debbie Hayton - in the Times - you can find links on this forum) and the erotic drive lies behind that. Women do not want to be walk on parts in someone's erotic fantasy in situations where they are undressed or vulnerable. and they don't want their daughters or grandaughters or pupils subject to it, either.
Men/males have a greater propensity to all sorts of behaviours: voyeurism; fetish; flashing ( self exposure); heavy breathing phone calls ( ask anyone who works on a help line). There is now plenty of evidence of males violating women's boundaries in order to achieve a thrill or to validate their 'identity'.
I come across men presenting as women quite frequently where i live - and it is very apparent that most are driven by eroticism and voyeurism. As with your example of Julia Serrano - women and womanhood are perceived in very sexualised terms.
We don't accept the term 'cis' here - because i've I've tried to explain to you on several occasions ( without response from you) - such terms form part of a whole ideological construct. If you don't adhere or buy into this construct they have no meaning - in fact it is quite insulting to suggest to women that they are just one kind of woman - and that males can be women too.
Women are adult human females. Being a woman has got nothing specifically to do with gender roles or clothing presentations.