I agree with your general message. I do agree that this mother (and all parents, really) should have done her best to plan for her child's needs. I disagree with other posters in that I don't think every situation can be forseen and planned for. Even though this child has apparently flown successfully many times, many people do not think she belongs on an airplane.
I understand the philosophy behind preparing your child for the world, as-is. But if someone hadn't stepped up and said the world isn't doing enough for my child and those like him, would we have mainstreaming in classrooms, assistive devices, wheelchair ramps, ASL, etc? No one is falling over themselves to make accommodations out of the goodness of their hearts, they had to be forced. So someone has to be "that person" or "that parent". There have always been and will always be those who: blame the parents for the disability, are jealous of the accommodations, think any extra help is "entitled", etc. It's a good thing some people don't care about naysayers