I worked for Carmax last summer as the inventory guy, so I drove nearly all the cars on the lot, as well as customer cars to either find the problem (poor fuel econ, lack of power, mysterious rattles, etc.) and I NEVER drove any of those cars hard, not even the Porsche Boxster, or the SVT Cobras we had. I drove each of those cars like they were my own. Except for the golf carts, then we drove them all at their limits, that was fun!
The only car I damaged was a 2001 Tahoe, I kinda introduced the rear 1/4 panel to a concrete light pole that was hiding in the blind spot at 2 mph. that did $700 bucks of damage right there.
Some people did come in with their Cobras and Saleen Mustangs and requested that no one drive them, and 9 times out of 10 we honored that unless it had to go to the dealer to fix, then either I (my boss knows I drive like an old man a lot of times) or my boss drove the car.
That guy is an a$$ and deserves any reprocussions he gets.