After he desperately lies to get the torture to stop (like torture victims do), you are tasked with getting rid of him. But Trevor breaks with the plan, drives the man to the airport, and lets him escape, all while lecturing the player on how pointless torture really is. He drones on about how "torture is for the torturer," and how "the media and the government" trick us into thinking it's a necessary evil. You can practically hear the "Bush Did 9/11" shirt the writer was wearing.
The game writers probably like to tell people this was all satire, but if that's the case, then why is there a goddamn achievement for torturing the guy with every tool?