Here's something to consider -
I am no expert, but I would imagine that someone with their hands fastened behind their back is going to find it extremely difficult to get back to their feet without assistance, which, I think we can all agree, would be unlikely to be forthcoming in this situation.
Therefore, why the need to kneel on somone on the ground, be it for one minute, or twenty, on their neck of their back, or anywhere?
Why is it necessary to do that at all?