I think what mathemajician means is that if the stream of data is random (in that the bits are independent random variables each with probability 1/2 of being 1) then Solomonoff induction converges on the uniform measure with high probability (probability 1, in fact).

I'm sure you knew that already, but you don't seem to realize that it undercuts the logic behind your claim:

The universal prior implies you should say "substantially less than 1 million".