"We should ground moral positions in ethical reasoning rather than contingent empirical findings."

I don't think anyone ever does that, I don't see how it's even possible. To use a spicy, hot-button example:

"The importance of race differences is evident at an intuitive level. Whether fear of black crime is legitimate depends on whether blacks do in fact commit more crime, and, if so, why. Whether black poverty and academic failure are the fault of whites, and therefore impose compensatory obligations on whites—perhaps to be discharged by racial preferences—depends on why blacks fail." -Michael Levin

"moral principles of human dignity and representation" ...I don't know what that means, much less why it should justify discriminating against certain race(s) in favor of others in employment.

But we probably have different perspectives due to different beliefs...about the relevant facts. I can't think of a moral issue to which facts are not relevant, unless morality to you means no more or less than "God said so"...but then whether or not God did in fact say such and such, whether a given scripture can be considered reliable, whether or not God exists at all, etc. are facts that we are likely to dispute, and which are inseparable from the moral question.