Rove didn't do that "singlehandedly". He had a lot of help. Another allegedly conservative pundit, Krauthammer, lit off wailing about O'Donnell's choice almost immediately after her primary victory. I leave the room to fetch a beer whenever that loser comes up on Fox News.
Yes he did. He harmed her campaign significantly on her primary victory night, with no help from anyone else. What someone else might have done does not lessen the impact of his hissy fit and trashing of O'Donnell at the worst possible time with a large election night audience viewing.