Brake rotors are rarely damaged by worn pads that are replaced within a reasonable mileage after the replacement sensors are activated (mechanical or electric). If you drive through mud, sand, or other small, abrasive material frequently, you will experience premature rotor wear and scoring. This will be accentuate if your driving style is 'rabbity', i.e. speeding up and slowing down with frequent brake use or feathering. I have found dramatic differences in rotor and pad wear traceable apparently only to the driver.
The recommendation that you request the old parts prior to any repair is very good, though, and helps reduce the chance of a dishonest business deal. So, what WAS his 'double-talk' excuse?