I don’t think that you have the story quite right. Maybe this is a different 19 month old, but it looks like the same one.
“Bye Bye Plane,” over and over, interrupting the flight attendant who was trying to give the safety speech, several times. The mother thought that the kid was just being cute. The stewardess disagreed. The mother made no attempt to hush the child so that the flight attendant could get through her little speech.
And, that is reason enough to tell the pilot she was threatened? Sorry, if it happened even half way as described, the flight attendant over-reacted, as did the pilot. I think it was even mentioned that she admitted to having had a bad day. Uh, well, I do too, but I still have to be professional at my job.