I am a corporate security manager, and have been working in the field for 12 years. No doubt the policy was to observe and report. There is a constant risk of being sued by a citizen for false arrest, assault and battery etc. The hands off policy is pretty typical in all private security. The company that hired them definitely know this and probably demanded that be the policy.
In all likelihood, if the guards stepped in and handled the girl, he would have either been sued or lost his job. I find it difficult for you all to fault these guys for not intervening. Jobs are scarce these days, and those that do work as security guards often do so because they cant find other work. If they intervened and got fired, they probably wouldnt get hired on as a guard with any other business.
For those of you that are asking them to 'turn in their man card', perhaps you are overlooking the fact that they trying to put food on the table for a family. Sorry, but I think that's a mans number 1 priority is to take care his own. I guess they could always intervene, lose their job, go on food welfare and then get bitched at for being black, jobless, and a social leech.
If you all want to gripe at someone, then point your fingers at our litigious society, not at three guys that are trying to stay employed.