In practice they want people of high ability who will contribute positively to the US, not necessarily geniuses. My friend who was supporting actress in some Netflix thing got in on that basis.
O-1 isn't a genius visa, it is for [1] Individuals with Extraordinary Ability or Achievement, the government website specifically calls out categories that are not research or engineering.
Why not both? I can see the argument for not having millions of unskilled immigrants crossing from Mexico but both Dwarkesh and the researcher/engineer would benefit the US. I don't think it's that hard to get O1 as a researcher/engineer - you basically have to get to the level where you present at conferences and are seen as an expert in whatever.
I don't think so, personally, because I see that podcast as entertainment rather than education, and I don't think entertainers should ever receive O-1 visas.
Legislators thought otherwise, when they explicitly created two subcategories of O-1 visas:
* O-1A: Individuals with an extraordinary ability in the sciences, education, business, or athletics (not including the arts, motion pictures or television industry).
* O-1B: Individuals with an extraordinary ability in the arts or extraordinary achievement in motion picture or television industry.
The reason is pretty simple. Entertainment industry depends more on specific individuals than most other industries. If you have cast a foreign actor for a role, you can't easily replace them with generic interchangeable talent. But that foreign actor is not magically allowed to work in the US. They need a visa that allows it. Hence O-1B.