They do, however, recognize the symbols (American flag, silo stencils, etc.) and recognize it might be tied to the same symbols and markings the NCR found at the Divide.
NCR hires a Courier to take the item there. They don't for a second think that anything bad will happen as a result, and neither does the player.
Player delivers package, leaves.
The package is a detonator that contains missile launch codes that just needs to get within range and start chatting with launch computers.
So it does. As Ulysses says, package "wakes up," sends the detonation signal to missiles locked in silo, earthquakes and storms result. Post-apoc wasteland because even more post-apoc.
Fragments of package (along with everything else in Divide) scatter, are scavenged and rebuilt, package ends up in a new frame.History repeats.
Quite an interesting bit of information.