A superhuman intelligence that understood the nature of human consciousness and subjective experience would presumably know whether QI was correct, incorrect, or somehow a wrong question. Consciousness and experience all happen within physics, they just currently confuse the hell out of us.

As I understand it, it makes a prediction about your future experience (and the MWI measure of that experience)--not dying. Is that not falsifiable? I suppose you could argue that it's a logical and inescapable consequence of MWI, and not in itself falsifiable, but that doesn't seem like an important distinction.

I don't see how Tegmark's paper is relevant to this question.