They could do that. However unlike Major Cook's orders, these are not voluntary. To recind them would be an admission that they don't want him to be able to get into a Court of Law, with the right to defend himself, and prove the illegality of his orders (it is up to him to prove though, not for them to prove the orders legal, because it's an "affirmative defenses") in this case a Court Martial.
Thanks for your clarification!