Yeah, Prinz dealt with examples of relativism in the book. Of course we don't agree on everything! Some people are revulsed by rape . . .but not the rapists. He just meant broadly, evolutionarily, as a group, humans emotionally have a negative reaction to things that become moral wrongs.
(Which has the chilling conclusion that we should be glad that rapists and murderers are not in the majority of people who were produced by evolution.)
Anyway, fun piece! Thanks for writing!