I don't think an atheist can claim moral objectivity. Many do, but I personally don't see how it makes any sense to do so unless you believe in a higher being/moral law maker.
"Of course, everyone will claim they respect someone who tries to speak the truth, but in reality, this is a rare quality. Most respect those who speak truths they agree with, and their respect for the speaking only extends as far as their realm of personal agreement. It is less common, almost to the point of becoming a saintly virtue, that someone truly respects and loves the truth seeker, even when their conclusions differ wildly."
-walsh
-walsh