User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-4902593-20130204090336/@comment-3146930-20130209235432

But if they closed the Doors of Death from the inside, that would mean someone would be trapped in-between the doors, so they would be trapped between Tartarus and the Mortal world. They could reopen them, but that would just start this problem all over again. Using my example above, you could close the doors from inside the hallway, but then someone is stuck inside the hallway.