I think it's very interesting what you're doing here with the map.
From my understanding, you are actually making a very plausible story for Nuketown. In BOII Nuketown Zombies, we can hear one of the main characters from BOII locked in the fallout shelter, in which case the Fallout Shelter is unlocked in this version of the map and you play as the main characters, meaning this takes place before the CDC and CIA show up to Nuketown. Very clever.