The files are within bsp, because addition of these maps is as far as i know, temporary and these maps will be ingame only for the duration of this contract thing. They will be gone after that, as would be the separate textures, models, sounds and such. If some map making guy would use these assets within the next 2-3 months, those files would be gone as soon as Valve presses switch and a lot of maps would be broken.
That being said, i had issues today with snowplow where the train was invisible, the objects also that damage the train, some textures were missing and so forth. It didn't happen on the first load of the map during session, but once the map was reloaded by the server, they were gone. There's a huge console spam on each of these maps so i'm guessing the game fails to load all the assets and fails for that reason. It happens also on Borneo so the map isn't broken, game is.