"So JAPAB; what is the word that you use for the half of the population that has a uterus, gets periods, may or may not gestate a baby, will have a menopause etc etc. What used to be called 'women' until very recently? How would you categorise those humans as a class?"
I don't think there is a simple word for that group of people. There never has been really. Even under the traditional definitions, there is no guarantee that a "woman" will have a uterus, periods etc. "Medically typical non-Y possessing humans"?
"So stop being gynophobic. Prove to me that changing the definition of women to include people with male biology isn’t going to harm women either individually or as a class."
If it does then it won't be the redefinition itself that does the harm, but bad laws that allow people to do thinggs on the basis of self-ID.
A bit likehow it does no harm to let people self-ID their nationality, but if they then went on to create immigration policy on the basis of pure self-ID, well that would be harmful to certain countries.