Very interesting theory, i have a feeling there is much much more to tranzit than people think, which should shed some light as to what is happening. Some noticable things i have picked up during playing black ops 2;
The bus driver t.e.d.d makes many references to a research facility and says thats where we are going, however never goes.
My understanding so far is that the map nuketown is based before tranzit because during the rounds you can still here the bus beep on that map, along with the characters from tranzits voices being heard from the bunker when you knife, finally the map discription of nuketown mentions a research facility so i think nuketown is the research facility t.e.d.d refers too and the characters escaped to the bus shelter. Also if you look at the map nuketown navada is very close to tranzit...