Nobody is calling “a universal decision theory a moral theory”. According to hedonistic utilitarianism, and indeed all consequentialism, all actions are morally significant.

‘Moral’ means regarding opinions of which actions ought to be performed.

Two different actions don’t produce exactly the same utility, but even if they did it wouldn’t be any problem. To say that you may chose any one of two actions when it doesn’t matter which one you chose since they have the same value, isn’t to give “no guidance”. Consequentialists want to maximize the intrinsic value, and both these actions do just that.

Of course hedonistic utilitarianism doesn’t require completeness, which, by the way, isn’t one of its tenets either. But since it is complete, which of course is better than being incomplete, it’s normal for hedonistic utilitarianists to hold the metaethical view that a proper moral theory should answer all of the question: “Which actions ought to be performed?” What could be so good with answering it incompletely?

The author is far from alone in his view that both a complete rightness criterion and a consistent decision method must be required of all serious moral theories.

Among hedonistic utilitarians it's quite normal to demand both completeness, to include all (human) situations, and consistency, to avoid contradictions. The author simply describes what's normal among consequentialists, who, after all, are more or less the rational ones. ;-) There's one interesting exception though! The demand to include all situations, including the non-human ones, is radical, and quite hard a challenge for hedonistic utilitarians, who do have problems with the bloodthirsty predators of the jungle.

In trying to refute The Moral Landscape: How Science Can Determine Human Values, in the way that the linked blog does, I believe that it’s quite unimportant whether or not

• only conscious minds can experience well-being,
• Sam Harris himself believes that only conscious minds can experience well-being, or
• well-being is the same thing as pleasure.

What the linked Darwinian response criticises Harris for, among other things, is that he doesn’t formulate a rightness criterion, despite that he claims that science implies some kind of impartial hedonism. But if there really is an implication it should be possible to formulate what is implied! Of course Harris should tell us more exactly which values he says science can determine. It’s hard not to suspect that Harris, in order to evade legitimate criticism questioning the existence of any implication, wants to avoid being more precise. The linked Darwinian response also claims that the strongest version of impartial hedonism is classical hedonistic utilitarianism (although not at all supporting that moral theory). The intrinsic value of hedonistic utilitarianism can be formulated in terms of pleasure over suffering, or in terms of well-being.

Richard Dawkins has actually been criticised for claiming that genes emotionally are selfish! Can genes be any more selfish than atoms can be jealous or biscuits can be generous? Yes, actually, to their effect. ‘The ethic of animals’, as described in the Darwinian response, is, as I read it, clearly not a moral theory which all animals consciously and reflectively understand and share through language, but rather the moral theory which animals closer than any other moral theory over time unconsciously tend to practice. They do that due to the ultimate biological cause of their behaviour, namely natural selection. Personally, I don’t find it any more nonsensical than the selfishness of genes, that the formulation of the ethic of animals is deduced from, not what animals reflectively think, since they hardly do, but, what they actually tend to do.

Reading the Darwinian response it’s also clear to me that it doesn’t violate Hume’s law. It nowhere claims that it’s right in any higher meaning to behave according to ethical fitnessism solely because animals behave according to it, which they, by the way, don’t really do, even though natural selection tends to make them come quite close.