My pt it could have been 6.5, any plane wasnt going to be moved until it was safe to do so, not only in regards to the plane and its passengers but to those on the ground dealing with the 777 as well.

After all it was an active runway under the control of ATC, so UA (or any carrier) could have been stupid and constantly ask if they can go fetch their plane, until ATC said Go theres nothing that can be done = no Fine for any plane sitting out there for any length of time that they may have had to sit there.

The fines come into play when the plane is under the control of the airline and they just let it stay there. I would assume maybe wrongly that if a plane taxis away from its gate and a storm hits and does not get ATC clearance to return to a gate then no fine, if they get clearance to return but dont for whatever reason then they can be fined.

If Flight 111 by XX is waiting to take off and its approaching 3 hrs out there and ATC told everyone waiting , anyone who wants to return to a gate can do so and they chose to stay put is alot different then ATC denying anyone permission to move anywhere at all and telling everyone to sit pat.