2 things:
1) A legitimate news source would be nice, not a blog.
2) Senior military leaders can order what they want. That doesn't mean those orders will be followed, especially if it was an order to fire on unarmed Americans. Those senior military leaders might just find themselves trying to prosecute thousands for mutiny, only to have the panels for the courts-martial find they were illegal orders.
#2 nails the problem with the whole idea, Doc. Of course Obama and his company of Leftist authoritarians have no idea that this is the way the military below his hand-picked generals actually think, since virtually none of them have any personal experience with the profession of arms as executed by US forces.
ETA - I'd also add that if our senior officers find out that really is going to be the litmus test, most of them will lie to pass it. Some of them would be willing to do anything they are ordered to do, some wouldn't and would just lie to protect their own asses, and some would say yea but rationalize it by saying mentally "Oh, this is really just about assholes like al-Awlaki, not real groups of US citizens in a domestic setting."