"I believe that if a tribe delegates, for whatever reason, their ethical decision making to a group with that sort personality bias then the morality that results in is perfectly valid." By what standard? Morally conservative people who make such a delegation without understanding the bias and its effects may be making a serious mistake with respect to their own values.

I agree that the broad liberal-intellectual moral personality that permeates academia, media, and Less Wrong is better by my (liberal-intellectual) standard and yours, but if we don't understand this process it will be difficult to avoid similar mistakes on our part. I wouldn't worry too much about letting slip the well-published 'secret' that most journalists, scientists, and other academics are politically liberal. The only special danger here is letting slip that a portion of these groups' support is due to personality differences rather than knowledge.