Best I can tell this is a laying down competition, not a laying down in the same position competition. And they get bathroom breaks. So yeah, seems like you could really stretch this thing out.
While true in most cases, that doesn't apply here. They were allowed to have books, their phone, and a break every 8 hours to use the bathroom. Succesptible people can form pressure ulcers in that time frame, but a healthy person with normal circulation and skin, and absent from moisture and friction, will not get bed sores.
This is the lying down competition, not the bedridden and in a coma competition. No post performance surgery required, or else the $350 prize doesn't go very far...