All the evacuation points on Saw have a sort of metal mesh flooring that your heal would get stuck in. It is simply un-safe and impractical to wear high healed shoes on Saw. Colossus also has the same flooring on the evacuation stairs on the lift so the attendants strictly should't have allowed you on wit heals, but due to the amount of people the attendants deal with at one time on that ride it can be easily missed whilst on saw the station batcher deals with each individual group. The attendent was correct to tell you to change your shoes as if there was a shut down you would have had a very hard time and it is part of their job.