According to Marketwatch the reason was not because Whitman hates Romney and his fundamentalist women hating cronies. She said that she could not leave struggling HP at this time. Whitman said that when she joined HP, she said she would stay through this turnaround.
“I knew if Mitt won, I would not be able to join a Romney administration, So I’m completely committed to HP.”
Whitman was unsuccessful in her 2010 bid for governor as she lost to Democrat Jerry Brown, who spent only a fraction of the $160 million she paid. Of course maybe she does not think that Mitt will win.