Yes -- and the important thing to remember is that the second view, which all of us here agree is silly, is the naive, common-sense human view.

No, it's not. The naive, common-sense human view is that sneaking into Jane's tent while she's not there and stealing her water-gourd is "wrong". People don't end up talking about transcendent ineffable stuff until they have pursued bad philosophy for a considerable length of time. And the conclusion - that you can make murder right without changing the murder itself but by changing a sort of ineffable stuff that makes the murder wrong - is one that, once the implications are put baldly, squarely disagrees with naive moralism. It is an attempt to rescue a naive misunderstanding of the subject matter of mind and ontology, at the expense of naive morality.

What makes the theory relativist is simply the fact that it refers explicitly to particular agents -- humans

I agree that this constitutes relativism, and deny that I am a relativist.

why should we do what we prefer rather than what they prefer? The correct answer is, of course, "because that's what we prefer".

See above. The correct answer is "Because children shouldn't die, they should live and be happy and have fun." Note the lack of any reference to humans - this is the sort of logical fact that humans find compelling, but it is not a logical fact about humans. It is a physical fact that I find that logic compelling, but this physical fact is not, itself, the sort of fact that I find compelling.

This is the part of the problem which I find myself unable to explain well to the LessWrongians who self-identify as moral non-realists. It is, admittedly, more subtle than the point about there not being transcendent ineffable stuff, but still, there is a further point and y'all don't seem to be getting it...