I think you need to contact Fbodfather or higher ups at GM about that. If GM is going to do that there will be alot of people that never buy another GM product.
I mean the put launch control on the car for you to do launches. They say this is a sports/muscle car for the 21st century. If they want to keep selling them they better not be voiding warrantys on silly stuff.
Did the car have a tune? Did the transmission have torque management adjusted or turned off. I would think as long as no to either of those the car should be covered and the dealer is just bullshitting you to get higher fees out of you for warranty work.