It's worse than that.
They define morality as obedience. That simply is not morality. It reduces morality to something completely arbitrary, as was demonstrated thousands of years ago by the Euthyphro dilemma.
Yes, the Euthyphro dilemma is traditionally about gods, but it applies to any authority. No authority can make you more moral, regardless of who or what the authority is. Trying to use an authority-derived moral system results in the most extreme form of moral relativism imaginable that makes mockery of the very idea of morality (e.g. it's moral if the authority commands it, but not if you command the same thing). It doesn't matter if the authority is a real god, a fake god, a preacher, the government, a cop, or an ethics professor, an authority can only demand your obedience and said obedience will not and can not make you more moral.