It appears this disruptive passenger was charged for costs incurred by the airline purely as a result of her unreasonable behaviour. She had a clear contract with Jet2; the terms of which are contained in their Conditions of Carriage. But by going over £5,000 she can be forced into bankruptcy and even though suing her in court might not yield much in cash terms, the publicity would be priceless. Even more valuable would be be "reality TV" type of fly-on-the-wall documentary when the bailiffs arrive and strip her house bare.
I don't care much for anti-social people and it is always nice to hear that they end up paying a heavy price for their unpleasant behaviour.
PM