The facts are that no books were banned; but the mayor discussed the possibility several times with the senior librarian, and met strong resistance to any banning on moral or other Grundyesque grounds. The mayor later threatened to fire the librarian, and only backed off due to vocal protest from the public. The librarian later resigned when Palin was running for her second term.
The fact is that she proposed and explored the possibility of censoring the publics access to books. The meaning of that fact is, to me, that she is potentially a dictatrix on moral premises, and therefore not suited to be a national leader.