What took this from being merely bullying and repressive to being creepy and totalitarian in style is that Dunham didn’t just make a general complaint. She then posted what looks like direct messages or text message between her and the American Airlines account, in which she enthusiastically provides detailed information about exactly where the conversation took place.
Scratch a lefty, and a Stasi informant bleeds. But if you make this sort of behavior even moderately unpleasant for them, they will stop. Wannabe block captains should be mocked, shamed, and shunned. And, of course, called out for the awful people they are.