Lots of good posts, thank you.
I am just browsing the NUS Women's section. The Lead Campaign is against violence and the objectification of women. The Women's campaign also seeks to support student parents. The main NUS history page highlights the women's campaigns on access to abortion. All worthwhile stuff. I am looking at the mobile site, so there may be more. Worth asking the NUS if it really wants these issues, affecting half the student population, sidelined; when there is a already a forum for trans* campaigns.
But in part, the NUS, like MN, is hamstrung by the law, which recognises the right of men to identify as women (and vice versa) and not face discrimination.
However, the law also recognises that women should not be discriminated against. And any other groups. Censorship is discrimination, surely, when it denies one group a voice and impinges on their freedom of speech. Allowing biological men access to women's bathrooms discriminates against women's rights to privacy (what about Muslim women who want to sort their veil out in female space, that is before you get to sufferers of previous sexual trauma etc or the basic dignity of using same sex bathroom facilities).
Women fought for access to higher education; they were excluded partly because of fears intellectual endeavor would harm their reproductive function. Women also fought for equal representation, for a platform which is being eroded. These battles took place a good hundred years ago, as others have said. Women are now supposed to deny the existence of their ovaries; or be accused of being transphobic.