The Founders recognized that an American's fealty should be to ideas and to Liberty, not to Authority. Any authority--even a president--is subservient to the central principles enshrined in the Declaration of Independence and the Constitution and any order that contravenes those principles is invalid and need not, must not, be obeyed. This UCMJ section was taught to me by Lt. Skinner, who contrasted an American soldier's obligation to disobey illegal orders with the the lack of any such option for a German soldier in WWII. "I was only following orders," he pointed out, was not a valid defense for any member of the American military.
Lawfulness. A general order or regulation is lawful unless it is contrary to the Constitution, the laws of the United States, or lawful superior orders or for some other reason is beyond the authority of the official issuing it.
Sgt. Gary Stein should not be forced out of the Marines for stating, promoting, and defending one of America's most fundamental concepts: that every citizen must learn, understand, and defend Liberty, even if that means defying the State.