It turns out the guy he was visiting Universal with when the banning occured was also issued a ban for that day alone. I can't remember his name, but he posted a video on YouTube of the same Fallon / The Rock event with Adam, and at the end he says he was asked "not to come back on park grounds that day."
If true, this also sheds light on this all being related to an incident which occurred that day alone, and not about incidents from years ago which Adam claims. I'm no lawyer, but I cannot realistically see how the park can legally kick out someone for the day, simply for being with a person who is under security radar. (If they can, then Tim Tracker had better watch out!)
So this new info leads me to believe that both Adam & his pal were doing something up to no good that day, whether shouting at the celebrities, or whatever, to warrant them both being asked to leave...Adam with the longer sentence due to his history. It would seem to me that his buddy would have strong grounds for a lawsuit if in fact they booted him for the day simply for "being there with Adam", and nothing more. No park or business would take that risk in today's sue-happy America.