Has anyone attempted to prove the statement "Consciousness of a Turing machine is undecideable"? The proof (if it's true) might look a lot like the proof that the halting problem is undecideable.

Your conjecture seems to follow from Rice's theorem, assuming the personhood of a running computation is a property of the partial function its algorithm computes. Also, I think you can prove your conjecture by taking a certain proof that the Halting Problem is undecidable and replacing 'halts' with 'is conscious'. I can track this down if you're still interested.

But this doesn't mess up Eliezer's plans at all: you can have "nonhalting predicates" that output "doesn't halt" or "I don't know", analogous to the nonperson predicates proposed here.