Maj. Cook wasn't seeking revokation of orders. He simply wanted to verify, because no one else has, the legitimacy of his Commander In Chief. And I for one am proud of him and appreciate the courage it took for him to do so.
Consider that the Obama administration is about to go after “rogue interrogators” who, during the previous administration, followed apparently legal orders to interrogate terrorist suspects.
Now Obama says the orders were illegal, and he’s going after them.
So maybe Cook is concerned that any actions he takes in Afghanistan will, in the view of the next administration, be deemed illegal owing to Obama’s illegal usurpation of the office.