Can you really see any professional pilot getting on an imponded plane and trying to taxi and take off without clearances, even getting it tugged to another part of the airport requires clearance and I am sure the tug operator would not want to get involved in anything like this either. Just seems a bit overkill to me.
There has been an A320 impounded at Glasgow for ages.
Was there not an incident of an aircraft landing at Prestwick at night with no clearance and no runway lights a while ago?