You are entirely missing the point here. Neither Carrol nor Kelley nor I argued that the one-sex model is better than or should replace the two-sex model. Our argument is that biological differences do *not* have to resolve themselves into two "opposite" sexes. Sex is a political interpretation of biological facts; gender is an ideological expression of oppression.
According to Stephen Jay Gould, we might as well argue for one sex (in which "man" is a minor modification of the universal "woman"), since we have a "single ground plan," as he puts it. According to Thomas Laqueur, pre-modern Europeans in fact saw the world through the one-sex model (in which "woman" was a lesser form of "man"). According to Will Roscoe, the Zuni had three genders. And according to Anne Fausto-Sterling, our current two-sex model does a great harm to at least 4 % of the population, so why not have a five-sex model?
The point is to argue *against biological determinism & the naturalization of gender*, to which the naturalization of the two-sex model has lent itself.
Yoshie