I think I need to pose this question in general.
I'm anybody to get all Aristotlian here or anything; but, something that has to bother people on all sides of the issue of whether or not there a moral truths that apply universally.
If so may people are convinced that there is no moral truth that applies to everyone, why do they still behave as if there were?
Really, some the most indigant, self-righteous people I've ever met are also people who have scoffed at the very suggestion that there is a moral truth.