Told by the police I can't fly over a certain area

I've been stopped by the police once or twice before just asking what I was doing and nothing else beyond a 2 minute conversation happened.

Today however I was flying around a university that is also within controlled airspace. I have a part 107 license and i applied for and received authorization to fly within the area.

About 10-15 minutes into the flight an officer knocked on my car door asking about why I was flying and where I was flying. Apparently the university has it's own tracking system and could actually track the flight path of the drone. I was not standing on university property. But parts of the flight path took the drone over university property.

My understanding was only the FAA could tell you where you can and can not fly your drone. I even mentioned that, politely, to the officer and he acknowledged the issue but arguing the law was beyond his pay grade and he was just there to enforce the ordinances the university had.

I wasn't about to argue with the cop, since no matter what the law actually is, it's an argument that wouldn't have ended well for me.

This is what's on the university's page regarding drone usage:

Unmanned aerial vehicles (UAVs), commonly known as drones, are not permitted to operate, take off or land from, on or over University of Michigan property.

U-M property is defined as any building or property owned or controlled by the university.

The law is described in Article XVI in the U-M Regents' Ordinance.

Violations of the ordinance can result in a civil infraction, misdemeanor, fine and/or impoundment of the drone.

Am I incorrect about only the FAA controlling airspace?