Using the Universal Distribution in the context of the simulation argument makes a lot of sense if we think that the base reality has no intelligent simulators, as it fits with our expectations that a randomly generated simulator is very likely to be coincise. But for human (or any agent-simulators) generated simulations, a more natural prior is how easy is the simulation to be run (Simplicity Assumption), since agent-simulators face concrete tradeoffs in using computational resources, while they have no pressing tradeoffs on the length of the program.
Using the Universal Distribution in the context of the simulation argument makes a lot of sense if we think that the base reality has no intelligent simulators, as it fits with our expectations that a randomly generated simulator is very likely to be coincise. But for human (or any agent-simulators) generated simulations, a more natural prior is how easy is the simulation to be run (Simplicity Assumption), since agent-simulators face concrete tradeoffs in using computational resources, while they have no pressing tradeoffs on the length of the program.
See here for more info on the latter assumption.