Tao, Perelman, Wiles etc. aren't math geniuses because they can multiply numbers fast (which is a super weird definition of "math genius" tbh). They're math geniuses because they answer really hard questions in creative and unexpected ways; ways that often open up entire new areas of mathematics.
An interesting intelligence emerges from a colony of ants compared to one. An interesting intelligence emerges from the relations of the various parts of the brain. An interesting intelligence emerges from the combo of techniques that have led to GPT and other surprising AIs. Same with a human, to two humans collaborating, to tribes to companies to cities etc. And likely same by combining/integrating GPT-4 type of LLMs with other tools and with other specific purpose LLMs - a greater unit of significance will emerge. (The non-predictability of this with current science is what is kind of scary to me.)
You're getting stuck on semantics.
I expect Tao, Perelman, Wiles, etc. can process/handle/deal with numbers much more rapidly than I can.
Now imagine if these folks could do the same, except 10x or 100x or 1000x faster, without having to ever be bothered with things like sleep or food.
This may not be a good definition of a "Math Genius" but it is reasonable to think that all or most "Math Geniuses" possess this skill. Speed matters.