I don’t specifically remember an instance where they said Bill Clinton used it, but his brother Roger definitely. However, Bill’s mentor was Orval Faubus.
I can’t produce details, but I do recall reading accusations that Clinton did. Given that he was a male and kind of a Southerner, it’s not much of a stretch to think that he used it at some time in his life.
And it also serves the purpose as an illustration of how stupid the whole thing is — condemning someone and suggesting that it’s somehow a reflection on his/her soul or character for uttering a word, no matter how long ago or at what age it was done. Especially when it’s done with political-motivation to smear.