“Right, the fact that he had printouts of the regulations permitting batteries with airline permission, and airline permission proves that he was the one who was uninformed.”
“Airline permission” is ultimately up to the captain. If the captain says no exceptions, it doesn’t ride. Period...
Except there's no evidence in the article that the captain was even aware of the situation, and the airline itself, rather than saying that it was the captain's decision, said "it appears we were in violation of federal disability requirements."