I think both Cain and the commission were in a bad spot. Had Cain fought and been permanently injured, while keeping silent, everyone would have been unsympathetic and told him he should have pulled out or revealed how hurt he was before hand. The commission obviously were made aware of his injuries due to the interview and would have been raked over the coals if they allowed the fight and Cain was permanently injured. Allowing the fight to go ahead has too much risks and I think Cain and aka figured this was the best exit route.
Does anyone really want to see Cain fight for 2 minutes and get seriously hurt in the process.