The problem is not and never has been that having good manners must interfere with acknowledging the truth. By suggesting that it is, one is pandering to the cretinous lack of judgment that falls into confusion or rage at social rules about “a time and a place for everything”. Thus the “love of truth” is mixed with and debased by the preening thuggery of “keepin’ it real”, as if Larry Summers’s attempting to open inquiry on the subject of sex differences in scientific aptitude is of a piece with some talk-radio boor’s trash-talk. Klavan is correct to say that there are things “greater than courtesy”. But if both Summers’s speculations about women in science, and insulting comments about someone’s appearance, accurately illustrate your definition of “discourtesy”, you’ve been spending too much time in lefty charm school.
I don’t think we’re going to advance the battle for “the preservation of Western rationalism and liberty” by accepting the “bad guys” confusion of courtesy with obsequiousness, with its concomitant confusion of real debate with consensus-seeking.