An infallibility hard to swallow

Is the atheist throat big enough to swallow the implications of moral non-realism?

“If we reject the possibility of objective morality, then we must say that our own basic commitments are _never_ wrong (unless, of course, they are _always_ wrong, as the error theorist maintains)… Subjectivism’s or relativism’s picture of ethics as a wholly conventional enterprise entails a kind of moral infallibility for individuals or societies. No matter the content of their ultimate commitments, these are never wrong. This sort of infallibility is hard to swallow in its own right.” – Russ Shafer-Landau, “Whatever Happened to Good and Evil?”, p. 17