Lead Balloon:
The difference with car park booms and wheel clamping is that the person is not imprisoned. The person can walk away.
Were the aircraft's occupants 'imprisoned' in this case and, if so, by whom? In the car park/wheel clamping example, you said the 'person can walk away'. Theoretically, the 'person' in the airport incident can do exactly the same by getting off the aircraft. Surely the person is only 'imprisoned' if the airline or airport operator prevents that from happening.