Because his vote was planned out in 1992. I do believe they all get together, figure out who needs to have the PR to vote one way or another, and guarantee the outcome they want. At that time, Joe apparently needed to come out as "we need transparency!!" so he was appointed to vote for it. Now, we know he really didn't want it public, so his vote can change. The votes aren't always real. I do know reps and senators will vote a way they don't believe to appease their constituents. They come out smelling like a rose (even if it's fake) and they know their vote doesn't really matter in the pre-determined outcome.