I don’t think it really works, for similar reasons: https://www.lesswrong.com/posts/y3zTP6sixGjAkz7xE/pitfalls-of-building-udt-agents
I also share your intuition that there is no objective prior on the mathematical multiverse. Additionally I am not convinced we should care about (other universes in) the mathematical multiverse.
I don’t think it really works, for similar reasons: https://www.lesswrong.com/posts/y3zTP6sixGjAkz7xE/pitfalls-of-building-udt-agents
I also share your intuition that there is no objective prior on the mathematical multiverse. Additionally I am not convinced we should care about (other universes in) the mathematical multiverse.