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.
Also, taking it to an absurd, think of /r/aww. Would you support having 50% of the stories on there be links to CNN/Fox/MSNBC? There's a line somewhere, and there are multiple ways to address it: have a separate section or site for political news (call it PHN), have specific days or a quota of political news, to try to keep on topic, allow it, but moderate it so it has something to do with the Hacker part of Hacker News, etc. Why not experiment. Even the most HN-addicted of us can probably live without this one part of HN for a week.
Yet, that's the necessary result whenever declawing becomes a topic - /r/aww then becomes not just political, but even very tribal.