Yeah, I suspect that Haidt's analysis is politically biased in favour of conservatives. He added Liberty as a principle or moral instinct to satisfy libertarians. And the upshot of his perspective is that he brings liberals/humanists down to the level of conservatives.

Humanism is based on freedom, reason, and creativity, not just on animalistic gut reactions. Conservative social Darwinism is much more primitive, so by alleging that both sides are equally emotional, Haidt is elevating conservativism to moral status and lowering liberalism/humanism to moral mediocrity.

The conservative feelings are bestial and thus pre-moral. Animals have the same instincts that generate their dominance hierarchies, so Haidt's analysis implies that morality is everywhere and thus nowhere in the animal kingdom.