Wait, wait, wait. DOES HORDAK BREATH!? We saw the whole Catra in a cage having the air sucked out scene and he was in the cage with her and it didn’t effect him. I’m sure there’s something out there explaining this but damn if it’s not going to make me wonder.
Also, this suggests something Horde Prime could have done. If the clones don’t require air then that means the Velvet Glove could have kept the corridors in vacuum and only keep the rooms that absolutely needed air sealed off. It would make it a lot harder for a scrappy team to sneak around the ship if they have to do it in a space suit. Fighting them becomes easier too because you either just have to breach the suit and then back off and let them deal with it (or die) or trap them in a pressurized area. And on those moments when you need air in the corridors, well just pressurize one run of it so you can lead your prisoners around to gloat at them over alien jello.