A: You took my quote out of context. Whether you consider yourself a Yankee or not, most people outside the U.S. consider all Americans "yanks" or "Yankees." When protestors in other countries shout "Yankee go home!" they're not saying that it's okay for Southerners to stay.
B. You're missing the point. You, being from the South, could call me a Yankee and I wouldn't care. And I doubt that few, if any, people in the Yankee-inhabited part of the U.S. would consider it an insult, either. To return to the original point of the thread, it would make even less sense for me to be insulted if someone from North Dakota called me a Yankee.