Please note that it wasn't the manager of the Kebab shop who invoked the dreaded "Nazis" epithet. I believe that throwing that around in Germany is a crime as well--it's the crime of inciting hatred or hurling abuse at someone. It's worse than road rage, of course.
For Herr Sarrazin to go looking for trouble, and then find it, probably serves his own purposes more than anything else. Germany is well on the way to a diverse future. Younger people seem fine with it. As the older German population dies off, so will this sort of nonsense.