JK, I said if I were a University police officer I would have called my superior. The person who called his was just another employee, not a U police officer and not versed in law.
I see that when I go back and read your statement. I apparently glossed over the statement about the office and disconnected it from the following statement.

If I were simply a parking attendant and called my superior and they said the same thing, I don't put too much legal stock in that??

If I were the Supervisor on scene I personally would have called a University Officer for assistance, not try to be an expert on the FL or Federal constitution by demanding he leave?
I have found more often than not, if the guy was directed, by anybody they deem a superior, damn the law and I'm going to follow directions.

but, the first 3 people simply demanded OP leave and did not attempt to effect a detention. The third university person was calling somebody. Maybe he was calling the campus cops.