I agree with the basic point of the article. I would say, however, that Cobb was quite possibly pulling a scam at the last minute, intentionally throwing a wrench into the words by pretending that prisoners were being rewarded with pleasure via the death penalty. I think he had probably planned and rehearsed his little speech of "Thanks" so that he could spring it on the warden and the world and just mess with people's heads.
He seemed like that kind of guy.
Most likly he was messing with heads, however I bet he was messsing with oh, ten milligrams of Valium on board.