He is not being charged with being AWOL. He is charged with missing movement. Your argument will not be heard by the court. He received a legal order, the evidence will show that without ever mentioning the President, and the evidence will show that he refused to obey it. It won’t take long.
Evidence is presented by both sides in a Court Martial trial. The UCMJ specifically states that the accused must be allowed to present his defense. The hitch is that the Military Judge, and not the Court, gets to decide if evidence is "relevant", before allowing it to be presented.
Well, that’s rather the POINT. He doesn’t think he received a LEGAL ORDER. AND his standing orders tell him not to obey an order that he deems illegal until he finds out whether it’s legal OR NOT! The burden of proof of submitting a legal order is on the COC at this point!