Howzabout tell your little hellion, “NO, The world won’t always adjust to make you happy. You better learn that soon or you’ll get your happy little ass kicked by someone when you pull this on the wrong person.”
It coulda been a teachable moment. That concept that nobody else cares about making the world simply perfect for them. If the “autist” really, seriously, literally cannot stop from scratching people when they cannot have a hot meal, the person should be institutionalized.
It's a teachable moment only if the subject is open to teaching, and depending on the severity of the autism that isn't always the case. It sounds to me like the mother knew that a melt-down was a possibility and instead of re-scheduling to another flight so that she could ensure her child did have a hot meal before hand, she rolled the dice and hoped the kid would make it through the flight they were already booked on. And when her plan went to crap then she expected the airline to save the day.
There are no more institutions. Or haven’t you noticed?