This is where things go wrong. The actual credence of seeing a hypercomputer is zero, because a computationally bounded observer can never observe such an object in such a way that differentiates it from a finite approximation
This seems dubious. Compare: “the actual credence that the universe contains more computing power than my brain is zero, because an observer with the computing power of my brain can never observe such an object in such a way that differentiates it from a brain-sized approximation”. It’s true that a bounded approximation to Solomonoff induction would think this way, but that seems like a problem with Solomonoff induction, not a guide for the way we should reason ourselves. See also the discussion here on forms of hypercomputation that could be falsified in principle.
This seems dubious. Compare: “the actual credence that the universe contains more computing power than my brain is zero, because an observer with the computing power of my brain can never observe such an object in such a way that differentiates it from a brain-sized approximation”. It’s true that a bounded approximation to Solomonoff induction would think this way, but that seems like a problem with Solomonoff induction, not a guide for the way we should reason ourselves. See also the discussion here on forms of hypercomputation that could be falsified in principle.