it's odd that LessWrong community norms go so far in one direction on one tradeoff and so far in the other direction on the other tradeoff (at least with regards to certain subjects).

Telling people they are wrong is almost explicitly about rationality, but we should definitely think about how to do that. If I'm wrong, I want to know that and there's a clear benefit in people telling me that.

I don't see any clear benefit in discussing politics here, so I'm not even sure what the tradeoff is. It's not that politics are not important, but that there's not much we can do about them.

I'd be very interested in a post explaining why discussing politics is more important than other things, not why politics is important, for this rather small rationalist community.

but also thinking that, say, telling certain people their AI projects are dangerously stupid is very important.

I'm not sure he has bluntly told that to anyone's face. I think he's saying these things to educate his audience, not to change his opponents' minds.

Personally, I suspect government action will be important for the future of AI

This I might agree with but it doesn't justify talking about other political topics. This particular topic also wouldn't be a mind killer because it's not controversial here and any policies regarding it are still distant hypotheticals.