I'm not really sure where to even begin there (the idea that men and women are immutable categories just sort of appeared in the Victorian era, so it's not as if anyone needed to invent it in the 20th century); it's hard to argue the logic in an illogical argument, even to play devil's advocate. I'd recommend Whipping Girl by Julia Serano for the history of trans positive feminism, and how it interacted with trans exclusive feminist movements.