Legg's text doesn't give any direct answer to the question at hand, but all the technical details in there, like the difference between "measures" and "semimeasures", are really damn important if you want to work out the answer for yourself. I know mathematics has many areas where an "intuitive understanding" kinda sorta suffices. This is not one of those areas.

Is this .pdf relevant? It certainly seems to be relevant, though I admittedly haven't read it all (or really even a large portion of it) yet. I've been learning about Solomonoff induction and found Legg's write up to be handy, but that paper seems to go into much more relevant detail.