I'm curious why you think you need calculus to evaluate which charities to donate to.

I don't really know what exactly I will need beforehand so I decided to just acquire a general math education. Regarding calculus in particular, in a recent comment someone wrote that you need it to handle a probability distribution.

Surely there's some evidence that would cause you to update in favor of "SI knows what they're talking about"...

What evidence would cause me to update in favor of "Otto Rössler knows what he's talking about regarding risks associated with particle collision experiments"? I have no idea, I don't even know enough about high energy physics to tell what evidence could convince me one way or the other, let alone judge any evidence. And besides, the math that would be necessary to read papers about high energy physics is ridiculously far above my head. And the same is true for artificial general intelligence, just that it seems orders of magnitude more difficult and that basically nobody knows anything about it.

I would update pretty dramatically in the direction of "They know what they're doing" if TImeless Decision Theory went mainstream...

That says little about their claims regarding risks from AI in my opinion.