Why would "refudiate" have to be a dumb mistake, rather than a deliberate and meaningful fusion of two words such as "misunderestimated" and "confuzzle" have been accepted as?
I don't think she did it on purpose. But it seems obvious to me what happened: she couldn't decide as she were speaking whether she wanted to say "refute" or "repudiate" (both were logical words to use) and, therefore, said something "in the middle". Doesn't seem to me to be a sign of stupidity -- it's the kind of thing that happens to all of us. Much ado about nothing.