What's a biological man? Not a Y chromosome, since they used to test Olympic athletes but found that the presence of a Y chromosome was not sufficient to identify men and women. (There are multiple genetic conditions that can cause this.) Many athletes had an unpleasant surprise at the hands of the IOC resulting in at least one suicide.

History and relevant link: https://en.m.wikipedia.org/wiki/Sex_verification_in_sports#:....

I disagree. If you look at someone who could have a female face, female voice, female genitals, hormone levels marked by medical professionals, had massive changes in muscle/fat distribution. This person will be seen to most passersby as a woman, they will face the same systemic disadvantages feminists will have been arguing against for hundreds of years. To argue that oppressive institutions for women should not be removed but rather amended to oppressive for a subset of women is not in any way feminist.

Actually the feminists of the 60's and 70's debated this kind of issue at length and there was a diversity of opinion.

Indeed, the TERFiest feminists out there are observed to often be first wave feminists.