What they are really saying is this: people can act rationally while being tortured.
That's possible. But consider that people rarely act rationally when not being tortured. And torture is adapted to make it harder to think clearly and rationally.
I don't know how reliable torture is, but it definitely does do something to cause truthful answers. It's adapted to impair rational thinking in humans. (This doesn't mean it was consciously designed this way, it could simply have evolved by people using whichever methods turned out the best results.)
It's easy to think, "There is no rational reason torture would work." But that is a mistake. Torture isn't about rational reasons. It's about hurting people very, very badly in order to coerce them and prevent reason from playing any role in the proceedings. Torture isn't about having a discussion.