It absolutely takes away from his career, because he ends it in disgrace. You can rationalize his "bad judgment" however you like, but to ignore the fact that his legacy in history will be one of "bad judgment" is disingenuous. Political concerns may be allowing him to save face and retire honorably, but he failed to live up to his duty as an officer, period.
Just so my view on this issue is clear, my position is:
1. When evaluating General McChrystal's entire legacy, his good and bad moments have to be considered. Otherwise, the picture would not be complete, much less accurate.
2. By recognizing that the General engaged in bad judgment, etc., one is not compelled to discount his positive achievements. The two are not mutually exclusive.
3. A little professional consideration in handling the General's departure is not a bad thing. Firing him outright might have led to some feelings of vindication among those whom the General offended. In terms of substantive policy, such a move would have accomplished nothing more than his resignation did. Worse, an outright firing might have had an adverse morale impact on the military. The General did the right thing in offering his resignation. The President did the right thing in accepting it.
4. With respect to message #9 concerning General Eric Shinseki (whose judgment on Iraq happened to prove correct), like General Shinseki, General McChrystal will soon be a civilian. As such he will be free to publicly express political opinions, including those related to the U.S. military strategy in Afghanistan, the President's policies, etc. Prior to then, the chain of command principle barred such conduct, otherwise we would not have been discussing the
Rolling Stone article, much less the apparent end of his military career.