Calm down man.

Personal opinion should rarely restrict a man from his duty to defend the Constitution.
If you were German, but had to fight the Germans to protect the world from Facist, Anti-Semitic rule, would you do it? It depend on your patriotism, nationalism, and a billion other factors. It however would boil down to whether you are going to fight for or against the U.S. If your not going to fight the Germans, then you should resign IMMEDIATELY.
Don't just sit there, and then when the call comes in you say "OOPS, sorry, no-can do man. I'm German! I can't kill my neighbors."

Overall
I'll admire his spirit, but thats more a political activist and like the courtmartial says 'conduct unbecoming of a gentleman and an officer.'