Didn't the holdouts hold out because they really DID want to sue the airlines, though? This is what I recall, what do you remember?
Law suits against the airline were made illegal by the law that paid the blackmail. Some could be banking on the law being overturned, but I don't know the motives of everyone who showed some backbone and did not take the money in exchange for not bankrupting the airlines, (when the Muslims were responsible for the events of 9/11).