Ah thanks. I should've been able to figure that out from your third thought experiment anyways.

I'm unfamiliar with the terminology "2-sampling", "2-world", "3-world", etc. and a quick internet search has not turned up anything useful. Could you summarize what they mean or direct me to a place that explains them?

I'm confused here -- if the coin's randomness really is fundamental, and not a property of our ignorance, then it doesn't make sense to say that a being is too computationally weak to predict it -- no amount of computational strength would allow prediction

He stated that the randomness is being provided by a pseudorandom number generator.

This model is missing a plausible evolutionary explanation for how U and C may have evolved. That's a pretty gaping hole because if we don't constrain U and C to being plausible under evolution then they can be given whatever motives, responsibilities, etc. that are convenient to fit the model to existing data (see Psychohistorian's epicycle comment).