How on earth can you apply your Algebra teacher's statement to History?  History has taught us how even the 'nicest' people behave when told it is okay to beat up a person with a different belief.  During the Civil Rights protests, anti-integration zealots attacked (killed) not only Blacks but anyone who defended them and their rights as citizens.  Nazis attacked  (killed) Jews at first, then anyone who helped them, then anyone they could label as 'lesser'.  I don't think anyone here is advocating for censorship of the airwaves.  As you say, flying the Confederate flag may be just a form of 'flippin the bird'.  

I may very well stop in at Pop's Smokehouse and try the Cheerwine; it sounds like fun, but not if I have to listen to any hate-filled rhetoric.  I have quite a few relatives who disagree me on things political, and we simply don't mention them when together.