But his concrete argument (while being factually correct) is irrelevant. No one
was tortured, but was
threatened with torture
In the case of Abu Zubaydah, in his first 2 months of capture he provided more information than at any other time. The "enhanced" torture techniques didn't start until about his 3rd month of detention.
In both cases, the threat of torture, among other future conditions that don't fall under the "enhanced" umbrella (simple solitary confinement, life in prison, unable to see family, etc) were enough to extract valuable information. Subjecting them to humiliating and physically brutal conditions did nothing. tl;dr: threatening torture can motivate people to divulge information, but performing it does nothing further.