The AA people I observed, including but not limited to the woman who closed the STL flight with empty seats and 5 people trying to get on the plane, were way more interested in clocking out then helping anyone.
You bring up two interesting issues. In the case of weather at an airport, are gate agents authorized to hold a flight and not close it out 10 minutes before departure? If not, where is that call made? When was the STL flight closed?
Second: will the employee be paid if they hang around after the flight closes?