As to the NCL late arrival, I would suggest focusing on the direction given by the cabin crew who are, after all BA agents for this purpose. They advised not to run for it, where to go for rebooking and the likely rebooking. The question of whether one could theoretically have made a run for it is trumped by BA's own actions here.

As to why BA and other carriers pay a lot of money to defend some claims, it is not about any one claim, but rather about the broader issue. If the story line were to shift that courts and schemes such as CEDR are ruling against consumers with a greater frequency, there is less motivation by consumers to pursue claims. BA deals in claims by the hundreds and no one claim really matters.