Because “woman” only has one meaning to him. But that meaning is biological, cultural, legal, behavioral, and temporal, and to mix them up is to use people for one’s own ends, rather than to treat others as they would be treated.
Consider how someone 150 years ago might have described a woman; how someone in Afghanistan or Saudi Arabia would describe one, how a Southern Baptist would describe one, and how an American lawyer in their legal capacity would describe one. Only the lawyer would want to know the context — because to the others, women don’t have enough agency to completely define themselves. That doesn’t eliminate others from assuming women have complete agency, it’s just some examples, with religious and national assumptions stroked broadly
Wendy P.