It's a good defence if you can prove that what was said is true. Which bit of the story do you claim is untrue?
The only thing I can see is the "legally necessary checking in of all personnel going airside" bit. Not sure where the law says that but it may well be covered under ICAO Annex 17, which is part of the Chicago Convention, to which the UK is a signatory.
The bit about sabotage is unproven AFIK but it's a reasonable assumption in the circumstances.