To me it seems obvious that ideas are tools made and modified by particular people for particular purposes. Ideas are not instantiated in the world. "Biological sex" as an idea is almost always a sciencey attempt to distinguish natural and normal sex/gender from unnatural and abnormal sex/gender. I am no more or less natural by virtue of being unusual. You do you, but I have no use for "biological male".

Edit: Perhaps I should add that usual sex and gender seem to me very obviously socially constructed.