This is an interesting discussion, and I think both sides have very valid points. It reminds me of the time when I was an officer in the Association of Shareware Professionals, and there was a divisive debate over whether members should discuss politics in their private newsgroups. This was in 1999 or 2000. Eventually we created a "soapbox" newsgroup where members could go to discuss topics like politics. It was very controversial at the time, but I was supportive of it. In the end I think it worked out well because it kept the other newsgroups clean. I don't think I ever posted in the soapbox newsgroup myself, but I thought it was a good idea to create a place for those messages. As far as I know, that newsgroup is still functioning today.
The technology for newsgroups is a bit different though, since one newsgroup's new posts didn't get mixed in with the others.
It seems to me that it would be easy enough to disregard politics threads if you aren't interested in them though, even if they show up in the new posts list. You see the title, say, "not for me," and skip it. At least that's what I do for threads that don't interest me. I can't possibly personally read everything posted here (over 140,000 messages).
The main reason I'm considering adding a politics and global issues forum would be to create a place for people here to discuss it in the "smart person" style. I think it would be a waste of space for people just to argue with each other.