You people are making it sound like this rooster is in a tiny box it cant move in. All you are doing is keeping him from being able to stretch UP.
Being in a room you cant stand on your tippy toes in isn't cruel.
Mind you, this only works with roosters that won't lean forward to crow instead. We have one rooster it works on, and one it doesn't. They a re both totterer at night in a dog crate till we let them out in the morning. They can stand upright fine, just cant stretch out.
I also assume it could be done in a cruel way, but it dosn't have to be.