OK, that specific EO applies to an importer other than a government agency bringing back M1 rifles and carbines that were loaned to other countries. That had actually been the law for years until the exception for C&R items was made in 1986(?).
But that is only part of the picture. I see no legal barrier to the president banning the Army from transferring any firearms or ammo to CMP. Under the law, the Army is ALLOWED to do that, not REQUIRED to do it.
In 1963, the Army was ready to release thousands of M1903A4 sniper rifles, with scopes, through DCM. They were also going to weld the selectors of M14 rifles and sell them to NRA members who were in rifle competition. After Nov. 22, both programs were abruptly cancelled. No law. No EO. No formal orders. Just the SECDEF issuing an order that he was told to issue. That's all it takes.
Jim