Wilky,
All to do with legal 'stake' claiming. You''l find that in addition to 'blocking in' an aircraft an officer of the airport concerned will also place a legal notice on or in the aircraft and in some cases they 'seal' the doors with a 'breakable' seal normally just a plasticised strip with a legal statement of intent on it.
And yes it has actually happened in the past where 'SAS' type missions have been pulled off by flightdeck crews and engineers to 'free' an aircraft from such circumstances. Not so easy these days though.