If I recall the context correctly, the point of talking about rape was that the naturalistic fallacy is about an overly simplistic reduction. You speak of the "physical construction" of prescriptions or obligations, whereas I posited culture as an intermediary. The roots of morality may be instinctive, but there were leaps of imagination plus plenty of trials and errors in the Upper Paleolithic that made for the origin of culture and of behavioural modernity. And culture made those instincts exaptations, giving them new, cultural functions. Those functions and the universal perspectives that support them became anti-natural (i.e. humanistic, at the expense of the wilderness), and that's what blocks the naturalization of morality.