I don't mean to pile-on here. You've taken enough arrows on this thread. I suggest that there is a legal definition that varies from the dictionary definition that you just gave. The legal definition -- and I'll see if I can dig it up for you -- basically say that lasting injury must be involved. It is not clear to me that waterboarding leaves any lasting effects.
They’re probably worried that the “lasting effect” will be mental or psychological.
Yeah, the guy may turn into a psychopathic mass murderer if... wait a minute... he IS a psychopathic mass murderer.