I assume we would want CEV to exclude the preferences of sociopaths and psychopaths, as well as those of people who are actually mistaken about the beliefs underlying their preferences.

I thought the idea was that, under CEV, sociopaths would just get outvoted. People with mutant moralities wouldn't be excluded, but, just by virtue of being mutants, their votes would be almost entirely drowned out by those with more usual moralities.

[ETA: Eliezer would object to calling these mutant moralities "moralities", because he reserves the word "morality" for the action-preferring algorithm (or whatever the general term ought to be) that he himself would find compelling in the limit of knowledge and reflection. As I understand him, he believes that he shares this algorithm with nearly all humans.]