But, EY also seems to be making a universalist argument, as least for "normal" humans.

If you have in mind 'human universals' when you say 'universality', that's easily patched. Morality is like preferring ice cream in general, rather than like preferring vanilla ice cream. Just about every human likes ice cream.

Because he talks about abstract computation, leaving particular brains behind, it's just unclear to me whether he's a subjectivist or a universalist.

1. The brain is a computer, hence it runs 'abstract computations'. This is true in essentially the same sense that all piles of five objects are instantiating the same abstract 'fiveness'. If it's mysterious in the case of human morality, it's not only equally mysterious in the case of all recurrent physical processes; it's equally mysterious in the case of all recurrent physical anythings.

2. Some philosophers would say that brain computations are both subjective and objective -- metaphysically subjective, because they involve our mental lives, but epistemically objective, because they can be discovered and verified empirically. For physicalists, however, 'metaphysical subjectivity' is not necessarily a joint-carving concept. And it may be possible for a non-sentient AI to calculate our moral algorithm. So there probably isn't any interesting sense in which morality is subjective, except maybe the sense in which everything computed by an agent is 'subjective'.

3. I don't know anymore what you mean by 'universalism'.

is there also no universally compelling argument with all of "us" as well?

There are universally compelling arguments for all adolescent or adult humans of sound mind. (And many pre-adolescent humans, and many humans of unsound mind.)