While it upsets me Jobs wanted the Mac a closed system, that is not why Jobs was fired. While some may argue there were a number of things that led to his axing, it all boiled down to Jobs having pissed off Sculley and Job's attempt to usurp the throne while Sculley was away on business. Had he remained loyal to Sculley, Sculley would have likely continued to look past Job's faults and would not have axed him.
Sculley was your typical big company CEO. So long as a machine sells and the company bottom line is boosted, that's all they really care about. It doesn't matter if it's open or closed to such top executives.