UPDATE: YouTube removed the video due to an apparent “privacy” complaint.
We ended up talking to Ivan for a bit, and he changed his tune once he realized he didn’t really have any facts to go on. He ultimately made some comments about respecting photographers’ rights and kept mentioning a courtesy card inside they normally hand out, but he really didn’t seem very prepared to tackle this issue for his superiors. It was interesting that a security manager of a major skyscraper in LA would come out to reprimand photographers and not be armed with courtesy cards, his own business cards, or any knowledge of the law. But, I guess they pay these guys just to reiterate.
The takeaway is this: Knowing your rights and standing your ground is essential. Undoubtedly nine out of 10 photographers security approaches at the Gas Company Tower apologize and leave immediately. The security staff is then emboldened to enforce a nonexistent law and trample on constitutional rights, and there is absolutely no incentive for them to do otherwise.
Interestingly, someone has filed a privacy complaint with YouTube due to the above video. How does it infringe on anyone’s rights? No face is shown, no last name is given; we’re on a public sidewalk discussing a policy that relates to photography in public. What an incredibly lame move from a very small person – someone who is perhaps embarrassed how he comes off? Just speculation, of course.
boywithgrenade.org 
I wish I were local and could join a group to go there on a semi irregular basis to train those guards. If enough folks went and confronted them eventually they might get the message.
Keep up the good work. As law abiding citizens, we must protect our rights. This is especially important when on public property.