I think this is the major hole in the argument, and in the "AI maximalism" position you present. There is no such thing as an omnipotent genie, or a magic eight ball that can answer any question. Any technology has limitations, and if you assume as a premise that the technology does not have meaningful limitations (or that the limitations are irrelevant, which is really what you said), the conclusions you draw will also make no sense. This is how you get nonsensical ideas like the singularity.
I remember the discussions and predictions when e-books or internet newspapers were first introduced. In 2026 they still sell actual newspapers where they print yesterday's news on large sheets of paper. People still pay for that instead of checking X for free. We all buy and read actual books. TV hasn't killed cinema and YouTube hasn't killed TV. Real world doesn't work in extremes.
Real world also doesn't have 'infinity'. You can't just use undergraduate engineering math to create a feedback loop and explode a variable to infinity. Things don't work like that.
What I'm getting at is that even if it isn't literally omnipotent, it's indistinguishable from the impact it's likely to have on society.