Ridge got it on then first try, the mom pretty much said that the kid gets violent if she doesn't get what she wants.
And that, to me, is an excellent reason for the airline to bring suit against mom. If she knew what her crotchfruit would do, and didn't plan ahead, she should have to cover the airline's losses.
Meanwhile, I still think there might have been a better way out for the airline. And, if I were mom's defense attorney, I'd argue a duty to mitigate damages.