Man, I'm not exactly a bleeding-heart type but even I would find that behavior on the part of the customer rude.

You know a better way to "hurt the evil owners"? Just don't go to that store at all. But asking a customer a question is not a crime (unlike your Nuremberg analogy), these "victims" chose to walk into the store (unlike Nuremberg again), and being needlessly rude is needless, not required.