That you, I and lots of people here share a morality that de-emphasizes or abandons judgments that stem from the purity/sanctity pillar does not mean that those moral judgments do not need to be accounted for by a theory of morality. Note that wedrifid's popular reply to your comment defends one of the few purity-based moral judgments common among the liberal/cosmopolitan demographic cluster.

The problem is Prinz actively conflates metaethical concerns -- concerns about the adequacy of a theory of morality based centrally on empathy-- and normative concerns about whether our moral system does a good job at making the world a better place, or something. The above examples of victimless transgressions are good evidence for his metaethical thesis but irrelevant for the normative thesis.