would not a police officer be covered under the "exempt class of person" or similar wording, which would invoke some sort of authority, which would be covered similarly under the state legislation somewhere in turn invoking the power to do whatever??
As for a reason for the person traveling - could have been stationed at/near OOL (ie Kingscliff, NSW - not even 10 minutes down the road from OOL) before transferring to the big smoke .. and may have an outstanding court matter which was being heard in the court at Tweed Hds. which is even closer to OOL.