Well I don't generally consider chess mastery to be a sign of genius. Or maths, or music either. Fundamentally they are not creative, generative activities. There's a reason they are called a prodigy and not a genius. Of course there are the rare genius composer (eg Mozart) or mathematician (eg Euler).

I consider mastery of anything to be a sign of genius. Someone out there is in the top .001% of skill for underwater basketweaving, and I think they're a genius in that category.

Mathematics is a creative activity, at least at the professional level.

If he wanted to prove his thesis, he should have adopted.

The famous book: https://en.wikipedia.org/wiki/How_to_Solve_It

You tell me. You’re the genius.