Haidt's argument is that color politics and other political mind-killingness are due to a set of adaptations that temporarily lets people merge into a superorganism and set individual interest aside.

This seems more likely to be part of a general set of adaptations and norms for being nice to those like you (often kin or tribe members who you have reciprocal relationships with) and not so nice to strange-looking outsiders, who are not in reciprocal relationships either with you, or with other group members - and are thus poorly motivated to cooperate with you. Such explanations are based on kin selection and reciprocity - and typically make little or no mention of group selection or "superorganisms".

There's a field known as "tag-based cooperation" - which is all about the game-theoretic basis of color politics. Here's one of the papers that launched that field:

• Riolo, R.L., Cohen, M.D., Axelrod, R. (2001) Evolution of cooperation without reciprocity.