I think he's actually arguing that there should be NO protected characteristics at all(DutchJazzer, feel free to correct me if I'm wrong). That businesses should be able to discriminate on any ground they want(sex, race, color, nationality, sexuality, etc.). He can argue that of course. Or he can argue for specific ones to not be protected characteristics. I still haven't seen any convincing arguments for that. I gave my reasoning why I think such laws are reasonable and even desirable in the previous pages.