I agree with Sangill... Rust proofing used to be a phenominal idea 15-20 years ago. Now the metal used in new cars is a much different animal. Not only is the steel less susceptible to rust, but the treatment used to treat, prepare and paint the various panels is much different.
I would add rust treating your vehicle will not void any warranty. They would have to prove that what you did somehow caused damage that lead to a warranty claim which is unlikely if not impossible to prove.
I would add rust treating your vehicle will not void any warranty. They would have to prove that what you did somehow caused damage that lead to a warranty claim which is unlikely if not impossible to prove.