I felt really shocked as I was editing your story yesterday. First, because you're very right that you probably could have gotten into serious trouble — even though you had California law and Los Angeles ordinances on your side.
That security guard had no legal right to do what they did. In theory, you should have been able to get them in a tremendous amount of trouble.
In reality, not so much, huh?
What's particularly instructive about this is that it happened in a very progressive location. Imagine what might have gone down in Florida, Texas, Oklahoma, etc. Well, it doesn't bear imagining, really.