I am generally quite hesitant about using the differences between humans as evidence about the difficulty of AI progress (see here for some explanation).

But I think this comparison is a fair one in this case, because we are talking about what is possible rather than what will be achieved soon. The exponentially improbable tails of the human intelligence distribution are a lower bound for what is possible in the long run, even without using any more resources than humans use. I do expect the gap between the smartest machines and the smartest humans to eventually be much larger than the gap between the smartest human and the average human (on most sensible measures).