At the risk of getting drawn in, I'll venture to say that the Cinemark in Aurora had no security guards because it's a cheap theater and guards cost money, and had a gun ban because gun bans are good (God forgive me for this pun) security theater.
Gun bans are good security theater?
Do you consider it a coincidence that Holmes chose the theater with the gun ban rather than one closer to his home or a larger theater with more people in which he could inflict more damage?
You might want to refer to the definition of security theater:
Ah. I would think that signs telling James Holmes that Cinemark is a bunch of sitting ducks would be bad security theater, given that James Holmes chose not to comply with those signs.
And I would think that you wouldn't be a gigantic asshole about this sort of thing a few days after the second deadliest school shooting in American history, but I'd be wrong wouldn't I?