Actually, the focus on “biological differences” does make the manifesto something other than an up-and-up discussion of the potential hazards of affirmative action, which is actually an issue that deserves careful consideration (and I’m a leftist!) But biological differences put the argument into another realm, one which justifiably pisses women off. We’re not talking about military combat here. We’re talking about something which, at its crux, involves sitting at a computer. There is no scientific evidence whatsoever that gender biology shapes personality in any meaningful way. Sure, there’s pseudoscience, and it often conflicts with other pseudoscience. And there is social conditioning. But you and the dude are talking about biological differences that shape personality. There is not one iota of evidence that such differences even exist.