We had an unusual situation some years ago on International Operations, Australian registered and owned Aircraft, our Chief Pilot (an Aussie) could NOT fly as a Captain only a First Officer while we were in US airspace, he was a Captain when outside US airspace, and always the Chief Pilot.
In what kind of operation?
The age 60 rule here applied only to Part 121 airline operations so you might have been affected if you were QF but otherwise....
Many airline pilots here transitioned to Part 135 charter ops upon turning 60.