Well, I don't have experience with that chassis but do have some thoughts on tire rotation.
So why do we rotate tires? I always thought it WAS because tires in different locations DO wear differently! What is the purpose of rotating tires if not to change the wear patterns before they get too severe and the tire has to be replaced?
But then, it's not hard to get bad advise, whether it is mine or their, is the question.
But just on what I know, it sounds like the tire guy was just not too inspired! Maybe too hot that day?