"...difference between, say, a 70 year old retired civil servant waiting patiently at a checkpoint and an Al Queda member attempting to evade said checkpoint..."

This is true, but I thought we were talking about a natural disaster here, not an Al Queda attack. Natural disasters of a large scale often bring out looters, some armed, and other assorted bad guys, looking for a free deal. They come in all ages and sizes, just like the good guys trying to defend their families, homes, and property. Those bad guys are the reason you saw officers from all over the country being sent to New Orleans, and carrying AR-15's as they walked the streets, going door to door checking on people. And to them, a guy with a gun, in camo or anything else, unless he is setting on his front porch, or the rooftop of his business, is a suspect until proven otherwise.

The mental image of a retired 70 year old civil servant in camo does bring a smile to my face...