I'm a conservative, so I might be biased, but the notion that Lesswrong is culturally unwelcome to lefties strikes me as not just wrong, but funny. In any given scan of the site, I'll see 3-4 things that offend me.
Threads will contain, not as the point of the thread, but just as background noise, as assumptions with which the writer presumes everyone will agree, atheism, pro choice stuff, polyamory (usually with same sex stuff relationships in there), discussions of how cool it will be once we turn out bodies into robots, etc.
I recognize that it is possible that the site is somehow also offensive to progressives and I simply miss out on all of the conservative talking points because they are transparent to me (fish don't see the water that they swim in, etc.), but I don't think that's the case.
I'm not claiming that LW is generally hostile to lefties, nor that there aren't things that happen here that might annoy righties or push them away, nor that overall it's worse for lefties than for righties. Only that one particular thing that happens here makes LW more unpleasant for lefties than it need be and drives some away.
(I would prefer LW to be a place where people with any political proclivities at all can feel welcome, unless those proclivities are severely and overtly anti-rational or so obnoxious as to render them unwelcome pretty much everywhere.)
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one. (Immediately before; refresh the list-of-threads page before posting.)
3. Open Threads should be posted in Discussion, and not Main.
4. Open Threads should start on Monday, and end on Sunday.