First, I will preface this by saying I have not driven a 2013 Camaro with this feature yet, so I am merely theorizing. If I'm incorrect, please correct me.
I did have Hill Assist on my last car. same idea, hold the brakes for an extra two seconds to give you just enough time to get rolling. with that system, it only applied the brakes just enough to hold the car from rolling backwards. Very light pressure will do this. In other words, it did not lock the wheels to prevent any and all movement. The purpose of this system is to let you start moving forward while it is still on.
OP, are you saying that in the Camaro, it applies so much pressure on the brakes that you are not able to move forward until it deactivates? If this is the case, it would be a step backwards. I would assume however that Chevrolet would not design a system such as this, as it requires you to guess when the two seconds are up. After all, once the hill assist releases the brakes, you would be in the same position as if the system did not even exist. To me, this wouldn't make sense.