The flight attendant is supposed to be trained to deal with stressful and awkward situations. The fact that the incident escalated to the point where a fellow passenger intervened, is a direct consequence of the flight attendant's handling of the situation. Regardless of whether the gate agent should have arranged for the stroller to be put in the hold, or that the lady may have raised her voice, the flight attendant should not have made a minor problem into a full-blown incident. The lady was travelling with 2 very young children, maybe catching a connecting flight, and was was under enough stress to look after her children as best as possible whilst travelling. She did not need some fat moron with the people skills of Hannibal Lectar to make her day even more stressful.