Whether or not you think the mother was inexcusably wrong for bringing the stroller on board, this does not at all absolve the flight attendant from using words that inflamed or worsened an emotional situation.  Unless you are trying to flee a raging fire, there is absolutely no excuse for nearly provoking a fistfight.  If there are any doubters, one only needs to observe the Captain's actions on the video.  There's no question that even HE thought the flight attendant was out of control.

As I wrote before, that kind of "let's take it outside" attitude might be okay at an outlaw biker bar catering to the likes of the Hells Angels, Bandidos or the Outlaws, but not on a passenger jet.