then we are even because I feel statements like this imply regional superiority and are masked as being proud of their region. I find that offensive.
I think that sort of sentiment certainly can come from a feeling of superiority, but not always. Unless, for example, you think every native-born US citizen who states they are proud to be an American is deliberately insulting every other country in the world. I myself do not believe that, but I do acknowledge that far too many people who proclaim themselves to be patriots of any country do believe other countries are inferior. I just don't think all of them feel that way, and I don't judge every statement of that sort to be rude unless I have other evidence of a superior/rude attitude.
To me it is not polite to be proud/feel superior about something that isn't an accomplishment.
I don't think it's especially intelligent or useful to be proud of something that you have no control over, but I don't think it's inherently rude. It might be, depending on how you profess or display your pride, but not always. I also don't think that "proud" and "feeling superior" are the same thing. Do you really think anyone who feels proud is being rude?
How is being proud of being Southern different from being proud of your race or your gender or some other thing which is not an accomplishment? I am white hence I am correct. Rude, not rude? I am a man hence I am smart. Rude or not?
I don't see those as equivalent to what's being discussed. Southerners have a reputation/stereotype for being especially polite, right or wrong. Ms. Quinn was making a humorous comment playing off of that generally harmless reputation, the same way a blonde person might say that they're more fun, or a redhead might joke about their fiery temper. None of those stereotypes are universally true, and I don't know anyone who believes they are. But most people are aware of them (in the US, at least) and so their existence can form the basis of jokes or anecdotes.
There is no generally known reputation or stereotype that white people are correct or men are smart, so no one professing those views would be making use of the cultural shorthand that the Southerner/blonde/redhead comments rely on. Even so, I'm not sure I'd call people who say your examples rude. I'd definitely think they were stupid, but whether they were rude would depend on exactly how they phrased it and in what circumstances.
There are, of course, common American reputations/stereotypes that are generally rude. Not all black people are good at basketball, and not all Asians are good at math, for example. Anyone stating that they were in a serious manner would quite possibly be rude, but might also simply be incredibly ignorant. I don't think ignorance is inherently rude, but it often accompanies and spurs rude behavior or attitudes such as racism so it can be hard to tell the difference. But even if someone states one of those untrue stereotypes - whether it's an ignorant/racist person who isn't black or Asian, or a black or Asian person saying it as a joke about themselves - they're not necessarily saying that ONLY black people are good at basketball, or ONLY Asians are good at math.