When there's a deluge of political stories, as in the last couple days, users heavily flag most of them. But there have still been plenty of major threads spending plenty of time on the front page. That's the status quo for HN: most politics are off topic, but not all. It's a delicate balance and an important one. Letting politics overrun this site would kill it.
There's no satisfying anybody about this: not the readers who want more politics, not the readers who want less, and certainly not the partisans on an issue. When you see something you don't like, e.g. stories being flagged or not being flagged, the mind leaps to "the other side must be manipulating this" as an explanation, but that's almost never the case. What you're observing is the behavior of a large community—divided in much the way society at large is divided—plus randomness.
If anyone has concerns about a particular post being manipulated they're welcome to email hn@ycombinator.com, but please don't post insinuations about that here. Unless you have real evidence, that's reliably an uncivil and unsubstantive move in discussion.