Folks such as myself (who were also against the dividend on the common stock, the MappleGate apology and any culturally significant departure from acting in Steve Jobs' legacy) make a largely abstract case against Einhorn's thought process and others like his.
Take it from a social science guy. It's not easy to make theoretical and philosophical arguments against the people from business school and come out looking good. The MBAs contend that that's because the social science argument has no merit. The social science cats have a tendency to get all uppity and ridicule the business school folks as intellectually inferior. (I don't do that anymore.)
Einhorn hit a couple areas that tread a bit closer to the theoretical. For instance, he makes the case that, contrary to the popular belief in tech that returning capital to shareholders tells the world we can no longer innovate, sitting on an idle pile of cash not only looks worse, it also has detrimental material effects.
All else equal and taken literally, it's tough to push back on Einhorn's logic. In fact, he won on Thursday. Apple will end up, one way or another, doing exactly what he suggests or some variation of it. That's because Tim Cook, while no stranger to Apple's renegade image, falls, quite obviously, much closer to the pragmatic end of the spectrum than Steve Jobs did. If things even got to this point, Steve Jobs would have told Einhorn to go to hell or complete ignoring the issue. Simply put, it would not be an issue because Jobs would not have let it become one and, presumably, Einhorn would have felt a lot less opportunistic and confident with Jobs manning the controls.