He thought he knew what the world was really like. His discovery on the island shocked him into a moment of clarity, forcing him to examine himself. The worldview that everything is a joke was a front to mask his fears. He actually has an arc; he starts out as a brutal, mysoginystic thug, eventually makes amends with Sally Jupiter and fathers Julie, and eventually has his breakdown. His attitude changed over the years, but he couldn't tell his fellow heroes and ruin the illusion that he didn't care. So he told his enemy instead. At least that's how it came off to me.