Cute story. It'd probably be funny, like, seeing it in a movie or something, but really, all that was accomplished was that it created a stressed out little girly who, assuming she found her bag, will still never know how it ended up checked and will likely blame the airline. Which is easy enough to do with UA for
real reasons, so there's no need to generate ill will for UA for
false reasons.
It would have been better had the flight crew been able to address it directly and honestly with with the infant female in steerage, so as she grows into pre-teen-hood, she begins to better understand cause and effect, and the consequences of bad behavior.
So a teachable moment was lost, and only bad karma (and useless confusion) was generated.