Considering the refugee doesn't have an actual underground level despite it being constantly hinted, probably out of performance considerations and game design, I see no reason for the Hub to do so, specially considering it is full of hostile NPCs put there solely for the purpose to make sure the player won't trivially sack the place. If you remove it, you no longer need to have the Hub as a permanently hostile faction just to make sure it won't be a trivial treasure chest, and considering what was done to the refugee center, I see now reason why this isn't the case anyways for there.