The rampant dismissal of so many restatements of your position has tempted me to try my own. Tell me if I've got it right or not:
There is a topic, which covers such subtopics as those listed here, which is the only thing in fact referred to by the English word "morality" and associated terms like "should" and "right". It is an error to refer to other things, like eating babies, as "moral" in the same way it would be an error to refer to black-and-white Asian-native ursine creatures as "lobsters": people who do it simply aren't talking about morality. Once the subject matter of morality is properly nailed down, and all other facts are known, there's no room for disagreement about morality, what ought to be done, what actions are wrong, etc. any more than there is about the bachelorhood of unmarried men. However, it happens that the vast majority kinds of possible minds don't give a crap about morality, and while they might agree with us about what they should do, they wouldn't find that motivating. Humans, as a matter of a rather lucky causal history, do care about morality, in much the same way that pebblesorters care about primes - it's just one of the things we're built to find worth thinking about and working towards. By a similar token, we are responsive to arguments about features of situations that give them moral character of one sort or another.
This is the interpretation I also have of Eliezer's view, and it confuses me, as it applies to the story.
For example, I would expect aliens which do not value morality would be significantly more difficult to communicate with.
Also, the back story for the aliens gives a plausible argument for their actions as arising from a different path towards the same ultimate morality.
I interpreted the story as showing aliens which, as a quirk of their history and culture, have significant holes in their morality - holes which, given enough time, I would expect will disappear.
On Wei_Dai's complexity of values post, Toby Ord writes:
The kind of moral realist positions that apply Occam's razor to moral beliefs are a lot more extreme than most philosophers in the cited survey would sign up to, methinks. One such position that I used to have some degree of belief in is:
Strong Moral Realism: All (or perhaps just almost all) beings, human, alien or AI, when given sufficient computing power and the ability to learn science and get an accurate map-territory morphism, will agree on what physical state the universe ought to be transformed into, and therefore they will assist you in transforming it into this state.
But most modern philosophers who call themselves "realists" don't mean anything nearly this strong. They mean that that there are moral "facts", for varying definitions of "fact" that typically fade away into meaninglessness on closer examination, and actually make the same empirical predictions as antirealism.
Suppose you take up Eliezer's "realist" position. Arrangements of spacetime, matter and energy can be "good" in the sense that Eliezer has a "long-list" style definition of goodness up his sleeve, one that decides even contested object-level moral questions like whether abortion should be allowed or not, and then tests any arrangement of spacetime, matter and energy and notes to what extent it fits the criteria in Eliezer's long list, and then decrees goodness or not (possibly with a scalar rather than binary value).
This kind of "moral realism" behaves, to all extents and purposes, like antirealism.
I might compare the situation to Eliezer's blegg post: it may be that moral philosophers have a mental category for "fact" that seems to be allowed to have a value even once all of the empirically grounded surrounding concepts have been fixed. These might be concepts such as "would aliens also think this thing?", "Can it be discovered by an independent agent who hasn't communicated with you?", "Do we apply Occam's razor?", etc.
Moral beliefs might work better when they have a Grand Badge Of Authority attached to them. Once all the empirically falsifiable candidates for the Grand Badge Of Authority have been falsified, the only one left is the ungrounded category marker itself, and some people like to stick this on their object level morals and call themselves "realists".
Personally, I prefer to call a spade a spade, but I don't want to get into an argument about the value of an ungrounded category marker. Suffice it to say that for any practical matter, the only parts of the map we should argue about are parts that map-onto a part of the territory.