“It will be assumed to be a legal order unless the defense can show Lakin had ample reason to think otherwise. As a rule of thumb, if the 4-star on down to the O-6 thinks it is a legal order, the LTC is expected to trust their judgment.”
If he cannot question the legality of his orders then how were all those guards convicted at Nuremburg? The prosecution specifically held that they should have disobeyed their orders and thus risked joining the Jews in the ‘showers.’ Those guards were caught between a rock and a hard spot - damnned if the did and damned if they didn’t. LTC Lakin is in an arguably similar position.
I doubt we’ll decide his fate here... except through prayer.
Here, Lakin was ordered to do something perfectly legal, deploy with his command, by an officer with lawful authority over that activity. The reasons for disobedience do not, therefore, involve avoidance of participation in an obviously illegal act. Consequently, the unlawful order defense is not going to be seriously entertained.
This is a bit complicated to explain, but there's nothing unlawful about a deployment order. An unlawful order is one that 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". It is quite lawful and well within his authority for a President or a Secretary of Defense, to issue a deployment order. Compare that with an order to "kill all the civilians". That order would be plainly against the Constitution and the laws of the US.
Now, perhaps an argument could be made that the person who issued that order was not authorized to issue it. That's certainly something that can be examined for a military authority. But, that examination for a President will not be entertained by a military trial judge because it's a political question, or so the Supreme Court has held when affirming such a decision by a trial judge in Michael New v. US.
I know that's probably not the answer you want, but that's the way the UCMJ, the MCM and the applicable precedent works.