It might also be true that after Aurora the non-gun public feels safer if they are assured that no one in the theater has a gun, legal or not, evil intent or not. The management understands that and that's why a "no guns" sign gets put up. I don't think there are many people who themselves are unarmed but feel they are safer if other everyday citizens are, given that CC permits don't usually come with extensive combat arms and situational management training requirements like badge-carrying police have to meet, and that's the general perspective, right or not, that non-gun people have of private gun carriers.
Is it possible that there was an armed off-duty police officer or two in the audience, but their training led them to the conclusion that engaging with the shooter in the bedlam and the dark would put too many innocents at risk? That might also have been the case with prudent "civilian" CCers. "An armed citizen could have stopped the carnage before it got as far as it did" is too simple.
It's also true that armed private citizens' coexistence with non-gun people in public situations varies greatly with where that happens because attitudes about guns are not consistent across the country. What is acceptable to the general public in Colorado, for example, wouldn't be close to what is acceptable in New York, for example.