"I take real offense when people insist I am a bigot just to make themselves feel good."
The best thing, of course, is that Jonah Goldberg really does feel offended. That is at it should be. That Goldberg's experience of criticism is unpleasant suggests that it has finally pierced the first layer of right-wing defense mechanisms -- the ones that transform criticism into an irrelevant or even gratifying experience. He is no longer at the "I must be doing something right" stage, or even the "I don't care if you're offended" stage. Goldberg is experiencing negative feedback as negative; at the very least, his nervous system is now as sophisticated as a tapeworm's.
The other nice thing about this line is the qualification. Goldberg can't simply say that he takes offense when people call him a bigot -- he has to specify that this is only the case when they've done so "just to make themselves feel good." In other words, he realizes that the charge is potentially legitimate and that he needs to qualify his defense if it's going to work. The caveat is an admission of anxiety that his critics could be right.
One might hope that the offense and anxiety Goldberg feels when people call him a bigot mark progress towards the day when he -- and perhaps the right in general -- actually grapples with accusations of bigotry, instead of frantically ignoring it or reflexively dismissing it. But even if this isn't the case, making the lives of bigots a little less pleasant is an end in and of itself.