I doubt that he has a source.
While I have never actually tortured anyone, we did act occasionally on information gathered by torture in Vietnam. If a person has the information you want, you can get it by torture, but if they don't, they will say whatever you want them to say to stop the pain. If you can be sure that you have someone who has the information you require, you can get the information from them, no doubt. But being sure you have the right person is a tough business and less than reliable.
There are plenty of psychological tactics that can be used without actually going to torture. I know that many would say that psychological pressure amounts to torture, but give the ones who would say that a choice between being kept awake by loud music and lights and having a few fingers broken, or smashed with a hammer and my bet is that they would opt for the psychological pressure.