The insanity is being so detached from reality that you think people shouldn't react to a rifle being carried around a department store. This is not the sign of a responsible, rational thinking adult. You know, the kind of person who should own a weapon. It's the sign of a blustering idiot.
Gun supporters are doing themselves absolutely no favors by acting this way. All they're doing is driving moderates on this issue away. If the NRA and its supporters would stop focusing so damn much on the power fantasy of owning a gun they might just find out they have support outside of people who own them. Playing so heavily to their base is only enticing idiots like the JcPenny Desperado here and galvanizing the anti-gun movement.
tl;dr: Stupid stunts like these are only securing more support for anti-gun legislation. You're bringing this shit on yourselves.