Touchy subject since I wasn't there.
For starters I have an issue with the whole idea of censoring everything and turning society into a police state for the sake of "protecting the children". That's the job of parents not society in general.
However, also consider that parents are responsible for abusing their children in many cases. A lot of those pedophille photos and such ARE taken by parents for sale, and some of them are taken in public places (playgrounds, etc...) as part of the "erotic" appeal.
The questions that come to mind here are things like how the kid was posed, was the father telling the kid to pose? What exactly did the entire scene look like at the time?
Plus I'll be somewhat honest here, if some "rent a cop" reacted like this it's probably a bigger deal than if a cop did it. The reason why is simple, a security guard exists to represent the interests of his employer, and keep things quiet. Things like "Code Adam Training" are as much to look good on paperwork, and so if something happens your bosses can point a finger at you and place blame for not having done anything (holding up a uniform and taking the blame for what goes wrong is pretty much the job description for security), whether you could have or not. Being in security is 99% of the time about covering your rear and keeping things as boring and stable as possible. Generally speaking when things get exciting that's a bad thing, especially seeing as it means the guys in charge are going to look for a scapegoat (who WILL be Security) just for having the quiet disturbed. Anyone who does this professionally learns this kind of thing quickly. I won't go into the exceptions which should be fairly obvious (but again are pretty rare).
At any rate if some security dude stuck his neck out to harass a customer/patron for any reason at a mall or whatever, he probably had a bloody good reason for it. Either that or someone with a bloody good reason (ie one of his bosses) told him to. That leads me to believe that the situation was pretty over the top, and probably the kind of thing where NOT intervening would have created more of a disturbance.
Just to point things out in a practical sense. Security guards basically operate as a representitive of the property owner, what kind of power that entails depends on the property, and of course how much backup the person is going to get from the actual owners when he does something. Where I used to work was on an Indian Reservation (differant situation) I *could* potentially have a lot of leeway (though mostly we passed that kind of thing over to Tribal Police, or State Polie we "invited" to have a station right there specifically to help defuse problems) but even so I wouldn't just casually harass someone like this because in the end all security officers are concerned about their job and their paycheck, your being paid for quiet, not for any kind of "results". The movie stereotype of the security officer who thinks he's a cop generally does not exist, even when dealing with security that on paper (or in certain kinds of situations) could operate on a similar level.
Even on a reservation, understand that nobody wants to come to a casino that operates like a police state. You don't WANT to keep people detained on property (hence why you have real police handy to get them off site). When security actually does something it's pretty much in the interest of the Casino due to some extrerior factor like say a liquor compact with the state that requires drinks stay on the casino floor, with a fine if someone is drinking an an unliscened area, or agreements about fines for minors caught gaming. You wind up with a back and forth between liquor comissioners or whatever running around trying to fine the casino and the security guards hired to prevent it from happening. So basically if your insistant about something that you actually do (and carry authority with) it's because there is money involved as far as the property owner is concerned.
All of this rambling is mostly leading up to pointing out how over the top this must have been to get some security officer to step in, or even the property owner for that matter. Unless the guy just started two days ago, anyone who holds a security job for long knows all of this (in a general sense).
