When Dr Shalizi writes the rhetorical question "why it is so important to you that IQ be heritable and unchangeable?" in the context of "'human equality' and 'genetic identity'" his tone is not that of scientific skepticism of an unproven claim but rather an apologetic defense of an embattled creed. Really, why is it so important to you what the truth is?

I read Shalizi differently, as asking something like, "Really, is it because you care about the truth qua truth that you find this particular alleged truth so important?" Far from apologetic, he is — cautiously, because there is a counterfactual gun to his head — going on the offensive, hinting that the people insistently disagreeing with him are motivated by more than unalloyed curiosity. It is not, of course, dispassionate scientific scepticism, but nor is it a defensive crouch.

My interpretation could be wrong. Shalizi isn't spelling things out in explicit, objective detail there. But my interpretation rings truer to my gut, and fits better with the fact that his peroration rounds off ten thousand words of blunt and occasionally snarky statistical critique.