How about everyone with kids stays locked in the basement until the kids are 20? What were they supposed to do? The kid was fine on the flight to their destination. How were they supposed to know the kid was going to throw a fit? Were they supposed to say "OK, I think the kid is gont to cry today, I guess we'll just cancel our return home & I'll miss my work tomorrow?"
It's impossible to know when a 3-year-old is going to go off. It happens.
Maybe they could have picked the kid up & walked around to calm them, but it sounds like the stewardess wanted that kid strapped in its seat. Which probably would not have helped calm the kid at all.
Hyberbole not withstanding ... children 5 and older are usually ok on airplanes
Not so much her as FAA regulations. Not the least of which would probably be the airline's insurance carrier. I can see the lawsuit now from the parents if something happened to that child because it had not be properly strapped in it's seat.
I understand that kids can be hard to predict and harder to control, but if he can't get in and be strapped in his seat, he can't fly, (the pilot can't even legally take off) and that is not the fault of the airline. Beyond that, they also have a duty to the rest of the passengers to not allow one to annoy everyone else. If the kid's not going to settle down, better to find that out while the plane is still on the ground than when it's at 30,000 feet.