Where better to talk about the politics of HN and Y Combinator than on HN? As far as political stories go, these are the most relevant ones to HN readers. Political stories about the tech scene, and related topics (such as political reactions to tech employees grabbing up all the real estate in certain tech-heavy cities like SF) are also very relevant.
I would be more ok with the banning of non-tech-related political stories/threads. But, I think a better solution than censorship would be tagging. Tagging would allow every reader to do their own filtering, and include/exclude what they felt was appropriate, rather than have those decisions dictated top-down.
On the other hand, I also understand the desire of the site owners/admins to guide the site to be what they want it to be, rather than what its users want it to be. That's definitely their prerogative, and much of it I agree with - particularly the censorship of hate speech, flaming, and trolling.
The guiding of this site towards more tech and less politics is also a desire I understand and commiserate with. There definitely are plenty of other political sites out there, where you can argue this stuff 'till the cows come home. But personally, I don't visit those sites, and would like to be able to discuss at least some of those topics -- the ones relevant to tech and to HN/YC, on HN itself.
Political discussion in many technical stories irks me, especially if it goes to the top. But I understand that it is sometimes valuable. Just like offtopic mentions of technical issues of the medium (horrible font etc.). Maybe it would be good to put it all to big bag called "offtopic" or something and put it always at the bottom of comment threads and stories list with ability to hid them in profile settings.