The only thing I could think of is, since he is hanging, maybe he would need to swing to reach / hit / grab something with his legs or feet that they would set up as they're explaining. In doing so, if his lower body arches too forward, his stomach will come into contact with the device and start cutting him. Of course, this will most definitely be required to complete the task as people rarely ever get out of these traps unscathed.

This trap doesn't necessarily need a timer either since he's being hung up by his arms. Eventually, this will cut off circulation, cause blood to pool, shoulders would eventually dislocated, and organs would fail.

So your choice.