Interpreting motives... We all have to do that when deciding if someone is credible. I don't see flight attendants just picking this family to hassle without cause. You have to assume that to believe this mother.
Your version seems more of a stretch to me.
... the stewardess was uncomfortable “because you have an unruly child who struck a woman on board.”
Mr. Kulesza was incredulous. “That was her mother,” ...
“Sir, we don’t differentiate between 3 and 33,” the AirTran supervisor replied.
You don't think the airline personnel overreacted, a tad?