Do you need a source or are you willing to accept that its true? Check this out then.
http://drorly.blogspot.com/2009/01/letter-from-lieutenant-colonel-dr-david.html
I am not required to obey unlawful orders but I must know what is unlawful. If I believe an order unlawful and refuse it, I can still be court martialled. If I prove the order was unlawful I will be ok, but otherwise I will face serious consequences. An officer would have to be insane to believe they could win a courtmartial against the President when the Supremes wont even hear these B.C. cases. So, unless the Supreme Court declares Obama a usurper, the military will follow his orders with all but very rare exception. (and those exceptions will be punished)
First: The officers oath, which is the same oath taken by the Vice President and members of Congress, says nothing about obeying orders.
Second, command no longer goes through the individual service chiefs. It goes directly from the civilian National Command Authority to the commanders of the Geographic Combatant Commands or the Unified Commands
IOW, this guy is either a fake, or some sort of non line officer, such as a Doctor, Nurse, or JAG (who would probably know).