The information about the warden being a total loser in the real world who hid in a hole comes from an Intel on paradox junction, and seemingly the crew on Totenreich is aware of this information based off what Dempsey says here.
Side note: love the warden’s character in this game. He deserted the confederates, hid in a random hole where he WOULDVE DIED, got lucky and teleported to the dark aether, and then backstabbed the dude that was helping him to gain power. Total sack of shit
Side Note 2: the two best voice actors in zombies are in this clip