If I remember correctly, he got hurt before the first pre-season game. Leading to Marv using the story of him being cut as inspiration for the team before a big game. "Well we cut Superman!"
http://redsix.swingshiftmedia.com/2002/02/26/from-buffalo-bill-safety-to-superman/
BTW, he did eventually end up on the sidelines for a game, December 1995, against the Dolphins, as a guest of the Bills. I remember because that was the first game I got to see at Rich Stadium. We also clinch a playoff berth that game with the win.