Good question
I suppose you could say that physical torture is not to be presumed.
The psychological value of holding him in a place where he can't know what we might do is worth something. I am certain that having him beyond the privliges of our justice system is a good thing for any continuity in interrogation.
I hope that whatever we do is not too damn medieval. Surely in the 21st century there are more effective methods than physical torture. I also hope that whatever limits we press at least produces results that will help save innocent lives.