It is my understanding that an unauthorized person is someone who is not, or will not, be granted a visa at the receiving country.
Standard practice in that event is, the airline gets to fly the unauthorized passenger back home on their dime (punishment for being stupid enough to let him fly).
In this case, someone made a bad decision, inconveniencing a planeload of passengers and wasting many gallons of jet fuel.
I hope the airline gets sued.