In 1992 he was not a serious candidate for any high office - but more to the point, at a convention, he probably said it to tweak some North Carolinian friend of his standing right there - or some such horsing around like that. I mean, it’s not like this was part of a keynote address.
I’m from NC, and it doesn’t bother me that Texans totally mis use the term barbecue.
If he was just bantering with a friend from North Carolina, that would make sense. If he were serious, the incident would still point to his being rude and boorish. We don’t need that in a candidate. The point is not whether he insulted a state or a person. The point is what the incident would say about him. I have serious reservations about Rick Perry, but I’m inclined to believe either that the whole story is a myth or that you are right about him just teasing with friends.