If you want to debate whether the OP was being hyperbolic, fine. I think it's splitting hairs and irrelevant to the real point.
He likely didn't believe that O is really the worst pitcher in baseball, it's just something you say in the heat of the moment to get the point across. It's semantics. He shouldn't be used in these types of games, that's all that matters, and I think a brief review of his numbers in comparison to the 5 alternatives makes that point difficult to argue against well.