In your section “complexity of conditioning”, if I am understanding correctly, you compare the amount of information required to produce consequentialists with the amount of information in the observations we are conditioning on. This, however, is not apples to oranges: the consequentialists are competing against the “true” explanation of the data, the one that specifies the universe and where to find the data within it, they are not competing against the raw data itself. In an ordered universe, the “true” explanation would be shorter than the raw observation data, that’s the whole point of using Solomonoff induction after all.
So, there are two advantages the consequentialists can exploit to “win” and be the shorter explanation. This exploitation must be enough to overcome those 10-1000 bits. One is that, since the decision which is being made is very important, they can find the data within the universe without adding any further complexity. This, to me, seems quite malign, as the “true” explanation is being penalized simply because we cannot read data directly from the program which produces the universe, not because this universe is complicated.
The second possible advantage is that these consequentialists may value our universe for some intrinsic reason, such as the life in it, so that they prioritize it over other universes and therefore it takes less bits to specify their simulation of it. However, if you could argue that the consequentialists actually had an advantage here which outweighed their own complexity, this would just sound to me like an argument that we are living in a simulation, because it would essentially be saying that our universe is unduly tuned to be valuable for consequentialists, to such a degree that the existence of these consequentialists is less of a coincidence than it just happening to be that valuable.
That has to be an edit… the final exam solution was found by the community.