Less Wrong isn't obviously a bastion of left-wing ideas, so it's possible whatever is filtering out conservatives from posting here is also filtering them out of academia.
When I started posting on LW, I was - depending on your terminology - very conservative. If there are any barriers that prevent conservatives from joining, then they didn't affect me. (Edit: this is anecdotal; I might just be an outlier.)
I should point out that my views have drastically changed since joining. Though I try to avoid aligning with any particular political group, libertarian-progressive might be accurate. I'm interested in seeing where other people in the community stand after the next census.
That sounds like an interesting question to put on the next census: What were your views before LW, what are they now, and if there was a change how much did LW influence it.
Summary: Current social psychology research is probably on average compromised by political bias leftward. Conservative researchers are likely discriminated against in at least this field. More importantly papers and research that does not fit a liberal perspective faces greater barriers and burdens.
An article in the online publication inside higher ed on a survey on anti-conservative bias among social psychologists.
The link above is worth following. The problems that arise remind me of the situation with academic and our own ethics in light of this paper.
I can't help but think that self-assessments are probably too generous. For predictive power of how an individual behaves when the behaviour in question is undesirable, I'm more likely to take their estimate of how "colleagues" behave than their estimate of how they personally do.
This shouldn't be surprising to hear since to quote CharlieSheen: "we even have LW posters who have in academia personally experienced discrimination and harassment because of their right wing politics."
While I can see Lammers' point that this as disturbing from a fairness perspective to people grinding their way through academia and should serve as warning for right wing LessWrong readers working through the system, I find the issue of how this our heavy reliance on academia for our map of reality might lead to us inheriting such distortions of the map of reality much more concerning. Overall in light of this if a widely accepted conclusion from social psychology favours a "right wing" perspective it is more likely to be correct than if no such biases against such perspectives existed. Conclusions that favour "left wing" perspective are also somewhat less likely to be true than if no such biases existed. We should update accordingly.
I also think there are reasons to think we may have similar problems on this site.