Kirk, I agree with what you're saying, and I understand the general public not understanding what may or may not be legal, especially in regards to firearms. I am not ok with the police not knowing, though I'm fine with them responding to a call, and cautiously checking out the situation (unfortunately we don't know what happened at the start). There is a common misconception that the AR holds no value as a sporting/hunting rifle and that is patently false on both accounts, and such drivel generally spews forth from the gaping maws of people who have absolutely no idea what they're talking about. The AR generally fires one of the more common varmint rounds the .223.
Of course, public perception is what it is, and even being very much a fan of the AR platform, I would check twice if I saw one slung over someone just walking around.