The way this sounds is that you are more concerned about politics as in people who take party positions and may feel excluded as a group when the majority of the community takes a different position. This is a slightly different issue i.e. party politics, and I think it is fine/a good thing, but it is also important to distinguish the two. This should essentially be under the same umbrella as personal attacks, as they are essentially the same thing.
I'd rather see HN go politics-free forever. Political discussions do not enjoy the same level of objectivity that technical and business discussions do. Frankly, it may be impossible to expect objectivity within political discussion because our political feelings are so deeply-held and tied to our individual upbringings, culture, and locale.
Unless HN can figure out how to give fair treatment to minority opinions, it's best to exclude these discussions entirely.
The forums on the internet should not be solely to affirm your opinions, but also to challenge them and allow growth as an individual.
The problem isn't with politics -- it's with the people misusing the voting system.
I would be surprised if this had much of an impact. I've encountered a lot of people even on HN who truly seem to believe their ideology is somehow 'fact'. Those who are sufficiently self-aware in this regard are probably not abusing the downvote button to begin with.