I am thinking that this might be one of the background pieces that Tom Clancy had right in his Jack Ryan thrillers. As I recall it, when you become one of the people who have authorization authority or confirmation authority, after passing Senate confirmation, you are issued a wallet sized card to carry. It has a number of ‘codes’ arranged in columns & rows and YOU, the card holder, decide which particular cell is the one that IDs you.
My GUESS is that Bubba forgot which cell he was supposed to use. Given the seriousness, I don’t think that the NMCC permits more than a couple before going to backup operations.
That only applies when a launch order is to be given. If Bubba realized at some point that he had forgotten, he could have had SecDef update his choice.