The mind of the true moral relativist is the mind of a slave. People who sincerely believe nothing have made themselves tabula rasa (pl., whatever that is in Latin), and will sooner rather than later not just find an ideology–which of course must necessary be expressed by concrete men–as master, but demand that they be forced to submit.
An interesting example is Michael Moore’s call for the rich–him–to pay more in taxes, without himself volunteering to do so. From his perspective, it is not “moral” until compelled.
This is a subtle point, and the point of congruence between what I have termed Sybaritic Leftism and Cultural Sadeism.