Don't dispute that at all...in theory.

But I have been in clubs late at night with delayed flights and was told it was policy to stay open until PAX had to leave to board the flight.

It's like the perennial debate about "should I wait at the gate for a potential UG or board and hope someone comes to get me."

There should be explicit documented policies that folks can depend upon, rather than being subject to the vagaries of what some agent wants to do on a particular day.