Rear brakes wearing faster because of high tongue weight?

GMs did not get electronic brake biasing until the GMT900s came out, so tongue weight shouldn't really be a factor. He may be confusing the system with a newer GM, or even Ford, since those do modulate rear brake-line pressure based on load by monitoring wheel speed (it uses the ABS computer, but it is not "pulsing" the brakes to accomplish the brake biasing).