Your point about regional politics is a really good argument for keeping political discussions out of Hacker News, for the most part. While (I'd guess) the majority of HN users are from the states, there's probably a healthy minority that are not and political discussions, which are almost always US-centric, generally do become noise and have low relevance to them. Even to myself as an American I already see too much political discussion on other sites like Reddit and Facebook that a place that is proactive in disallowing the discussions is a breath of fresh air (or bits, I guess).
I understand it's a little contentious to remove an entire topic of discussion, but I also welcome this and if the experiment goes well I would like to see it go longer term. I'm guilty of engaging in political discussions on HN but I try to moderate my words, but I know there are many who don't moderate their words in part or at all and especially because of how polarized politics seems at the moment (in the US at least) it's maybe a smarter decision to not allow people the opportunity to not moderate their words.