I have a similar question in the Ask Al queue:
http://www.camaro6.com/forums/showthread.php?t=516314
My guess is that it's more about how GM expects the cars to be driven rather than the car itself. I understand the comment about the aero, suspension, etc. playing a role in keeping the ZL1 1LE in the throttle a little longer, but I can't imagine that difference being significant. If that were the case, GM would probably need to have different oil recommendations for each road course too because the difference between track layouts would be far more significant in terms of braking vs acceleration time.