I think the dislike is visceral, coming from the same place that makes incest feel icky. Haidt's research seems to show people feel moral conclusions first, then rationalize them. I think it possible that a fairly large percentage of conservatives experience an intense visceral disgust for any blatant disregard of group binding moral foundations.

But my conclusion from that is not that conservatives should be vilified; just that we need to understand that the issue of group --vs- individual moral emphasis is a lot more than just a friendly disagreement over facts. The OP is making the point that we need to take group-binding dynamics seriously, both in understanding and using them to our advantage.