Just watched 60 minutes recording. The story/timeline keeps changing. Seems now the security guard was shot before the start of the massacre. We normal people can't think like a nutso, it goes against our ingrained sense of right. Therefore we have a hard time understanding because we can't imagine being in his shoes.
If you rent a room or suite, you do not have to have the linen changed, or room cleaned. Just keep the privacy sigh up. Does anyone really pay much attention to someone carrying suitcases in? Even long guns that are not "takedown" can still be disassembled stock from barrel making it shorter, then put back together in the room.
As for the founding writers of the bill of rights forseeing everything, they couldn't. But they also couldn't forsee telephones, TV, radio, internet, all things that are protected by the first amendment. I think if you could show then the weapons and power of modern governments, they would say that none of the things we see should have been allowed to even start. That is why they wanted the civilian to have available what was state of art weapons at that time. You cannot discount the ability of poorly equipped LOCALS to expel foreigners. Look at the history of Afganistan, and other places where a ragtag army wore out the enemy.