Well's account on the face of it makes you sympathize with her decision. And you could definitely make the case that she has every right to decide if a discrepancy is OK for flight, even if the MEL ays so. An inop APU on an EOPS flight is certainly one I would have to consider as a No Go.
However, for the rest of the story - she depleted the battery doing multiple APU starts, ignoring the start cycle limitations and displaying a lack of systems knowledge. Then she compounded the situation by making two announcements, one on tHe aircraft and one at the gate after the aircraft was deplaned, telling the passengers that US Airways was unsafe and they wanted her to take an unsafe aircraft. Capt. Wells also told the passengers to refuse to board any other US Airways aircraft and to force the company to reaccomodate them on a different carrier. That was when the company had her leave the terminal.