HP's newly departed Jon Rubinstein has explained his reasons for going in an interview Friday. He clarified to The Verge that he had planned to leave not long after HP bought Palm and agreed to stay one to two years, both to help transition webOS to HP and out of affinity with Personal Systems Group head Todd Bradley. Whether or not the TouchPad succeeded was incidental, as Rubinstein had already decided beforehand that he wouldn't stay permanently.
