any prior that doesn't assign things zero probability has this property
Oh yes, so it does. Let me therefore be both more precise and more accurate.
Let p be an Occamian prior in this sense and q any computable prior. Then as cousin_it remarks "a computable human cannot beat Solomonoff in accumulated log scores by more than a constant, even if the universe is uncomputable and loves the human"; in other words, whatever q is -- however much information about the world is built into it in advance -- it can't do much better than p, even though p encodes no information about the world (it can't since what the theorem says is that even if you choose what the world does pessimally-for-p, it still does pretty well). This is not true for arbitrary priors.
a computable human cannot beat Solomonoff in accumulated log scores by more than a constant, even if the universe is uncomputable and loves the human
Well, since Solomonoff is uncomputable, this isn't really a fair comparison.
In two posts, Bayesian stats guru Andrew Gelman argues against parsimony, though it seems to be favored 'round these parts, in particular Solomonoff Induction and BIC as imperfect formalizations of Occam's Razor.
Gelman says: