(This should_T terminology was discouraged by Eliezer in the sequences, perhaps since it invites incorrect moral-relativistic thinking, as if any decision problem can be assumed as own by any other, and also makes you think of ways of referring to morality, while seeing it as a black box, instead of looking inside morality. And you have to look inside even to refer to it, but won't notice that until you stop referring and try looking.)
I had no idea what Eliezer was talking about originally until I started thinking in terms of should_T. Based on that and the general level of confusion among people trying to understand his metaethics, I concluded that EY was wrong - more people would understand if he talked in terms of should_T. Based on some of the back and forth here, I'm revising that opinion somewhat. Apparently this stuff is just confusing and I may just be atypical in being able to initially understand it better in those terms.
In You Provably Can't Trust Yourself, Eliezer tried to figured out why his audience didn't understand his meta-ethics sequence even after they had followed him through philosophy of language and quantum physics. Meta-ethics is my specialty, and I can't figure out what Eliezer's meta-ethical position is. And at least at this point, professionals like Robin Hanson and Toby Ord couldn't figure it out, either.
Part of the problem is that because Eliezer has gotten little value from professional philosophy, he writes about morality in a highly idiosyncratic way, using terms that would require reading hundreds of posts to understand. I might understand Eliezer's meta-ethics better if he would just cough up his positions on standard meta-ethical debates like cognitivism, motivation, the sources of normativity, moral epistemology, and so on. Nick Beckstead recently told me he thinks Eliezer's meta-ethical views are similar to those of Michael Smith, but I'm not seeing it.
If you think you can help me (and others) understand Eliezer's meta-ethical theory, please leave a comment!
Update: This comment by Richard Chappell made sense of Eliezer's meta-ethics for me.