Environmental damage is another word for acid rain, bird poop, etc. It's not a defect in the paint which would be warrantable. It is an outside factor that has damaged the paint which is not warrantable.
This distinction is very clearly laid out in your owner's manual. It very clearly states that environmental damage is not a warrantable item, but in the interest of customer satisfaction, Chevrolet(GM) will correct such damage during the first 12 months of ownership. The dealership is merely telling you what the Chevrolet(GM) policy is. They aren't trying to blow smoke up your butt as you allege.
Touch of Class is an aftermarket paint sealant. It has no connection to GM nor Chevrolet, but is sold by many new car dealerships as an inflated package. It is good stuff, but doesn't perform miracles. It is a paint sealant. No more, no less. By itself, it will not correct any environmental damage. Buffing the paint is the usual method of removing mild acid rain and mild damage from bird poop. The TOC is merely to seal and help protect against future damage.
$600. for a buff and TOC application is pretty much a ripoff.