I think (pace Mother's comments upthread) that what this sort of borderline case does is to throw into sharp relief the two viewpoints. To my mind, it's a bit like abortion - either you are pro choice, or pro forced pregnancy. There really isn't a middle ground (much as some people would like there to be - "abortion's alright but only if the reasons are sufficiently good and the woman wears sackcloth and ashes afterwards").
In this case, either you think transwomen are a subset of women, in which case, all transwomen count - even Liane Huntley, Jessica Winfield, Davina Ayrton, Lisa Hauxwell, Kathy Brannen. You can't say "we'll have the nice accountant convicted of fraud who has dysphoria and count her as a woman, but Liane Huntley is taking the piss." Or you say transwomen are a subset of men, in which case by all means present, dress, call yourself whatever you want - but don't come into women-only spaces.
Personally I believe the latter. Transwomen are men. There's nothing wrong with that - they are men who feel more comfortable in dresses, wearing makeup, calling themselves by traditionally feminine names, rejecting the trappings of toxic masculinity, and more power to their elbow for doing so. I'll even call them "she" as a courtesy, just as I will refer to a priest as "Reverend" or "Father" even though I myself am an agnostic. (Actually I've said this before but I'll repeat it here - religious tolerance is the best model I can think of for trans issues in a liberal society - by all means believe whatever you want, but do not try to force me to believe it too, or claim that it justifies actions which impinge on my freedom to act in accordance with my belief set). But they are not women. They do not become women even if they have their penis removed and have reconstructive surgery.
Oh, and that courtesy of calling them "she" depends entirely on them doing me the courtesy of shelving their male privilege and acting properly. The moment they start to swing their metaphorical dick around, whether by threatening rape online, or as in this case, actually committing rape, they lose the right to that courtesy.