How is it a mistake? The political environment favored JD. Sarah's endorsement meant nothing when you boil it down, and even JD said that he understood why Sarah endorsed McCain. I bet JD will support McCain shortly.
She said she would campaign for McCain right after he lost the presidency, way before JD even entered the race? Why is this breaking news? I'll tell you why. JD was simply a horrible candidate who would have lost in the general anyway, and the anti-Palin brigade need a strawman to blame.
I guess when you have PDS things like keeping your word are irrelevant.