Guns at a presidential event and collectors' rights

A bit off topic I know, but last night a US collector pointed out to Dave Welsh (in relation to his ideas of licencing all metal detector use in countries which have antiquities laws) that "Here in America, rifles, for the most part never have and do not need a license" which in a way surprised, but then again did not surprise me.

Then today there was some news coverage of some irresponsible jerks who turned up yesterday at a Presidential rally in Phoenix Arizona openly carrying loaded arms, including an Armalite 15 assault rifle. Apparently "Arizona law has nothing in the books regulating assault rifles, and only requires permits for carrying concealed weapons. So despite the man's proximity to the President, there were no charges or arrests to be made". (Speaking as a Brit), how dumb is that? As CNN newsman Rick Sanchez in Atlanta (Georgia) says with reference to this

"just because you can do something, does it mean you should"?

I personally think this is a point that can be made with regard to certain things that go on in portable antiquities collecting, where "it's legal innit?" is supposed to the the only justification needed.