I’m with you here. Even if you has the “nuclear codes,” you would need unrestricted access to the detonation communication system. Which might get noticed when detonation orders started coming through Twitter. It’s absurd to think anyone but POTUS could fire a first strike nuke without full access to the triggering systems. And if they haven’t put bio readers in that system by now, they are idiots.
The nuclear codes are changed on a regular basis. Realistically, probably DAILY.