Inside the AI, whether an agent AI or a planning Oracle, there would be similar AGI-challenges like "build a predictive model of the world", and similar FAI-conjugates of those challenges like finding the 'user' inside an AI-created model of the universe.

Isn't building a predictive model of the world central to any AGI development? I don't see why someone who focuses specifically on FAI would worry more about a predictive model that other AGI developers. Specifically I don't think that even without Singularity Institute there would still be AGI people working on building predictive models of the world.