so much of EY's philosophy appears to build directly on his interpretation of QM.

Is this really the case?

I got this from Quantum Explanations:

I think I must now temporarily digress from the sequence on zombies (which was a digression from the discussion of reductionism, which was a digression from the Mind Projection Fallacy) in order to discuss quantum mechanics. The reasons why this belongs in the middle of a discussion on zombies in the middle of a discussion of reductionism in the middle of a discussion of the Mind Projection Fallacy, will become apparent eventually.

That is, Eliezer brought QM up at all as part of a philosophical discussion, because he felt he had to in order to make his philosophical points. You may then argue (as you seem to in your comment) that he did not in fact have to bring in QM to make his points, but he felt he had to, per that quote.