I'm going to guess she was going to be an ass

Why did Steve Schmidt stop Sarah Palin from speaking on Election Night:

...his decision to deny Palin an election night speech as a nod to the fact that the concession is a “singular moment” in American public life.

“It begins the process by which power is transferred peacefully,” he said.

In other words Palin desperately wanted to upstage McCain and kick off the 2012 campaign four years early by being an asshole.