I haven't really noticed politics of other countries get flagged that much, does it? Other than stuff that looks like propaganda from one country against another, that seems to get quickly flagged.
Finally I don't know what makes you think that HN is an unrelated to American politics forum, given that the guidelines of what the forum is for is quite lax.
Currently on the front page I see three stories that are not tech related, if I expand the definition of tech to include anything math or science related, there is really only one story, ironically this one that you posted in.
Often however I can find as many as 6 stories on the front page that are not tech and not any politics, as HN also handles art, history, and writing quite well.
But for some reason you seem to think it's a place for tech, and American politics should be kept out, which I find somewhat funny.