Just as an A/G Radio Operator can pass on a clearance from an ATCO "London Clears you to enter controlled airspace on track Daventry..."
They can also pass on a message from the Airport Authority, who do have the right to restrict landings, proscribe parking areas etc.
I personally would probably word it like this:
"The Airport Authority asks you to park to the North Side of the hangar on your right" for example.
I'd be surprised if a Pilot said "No" without a good reason!
Phil