Snow blowers and riders and tractors - load testing is hard and as a service dealer for over 50 years, I want those tests when ever possible. If they are involved with the trade and you are so concerned, if it were me, I would be testing that tranny again before trade. There is nothing wrong with being an effective service center and testing things. Maybe the service guy was told, if you called ahead, to go plow your way out and leave it where the customer can get to it without wallowing in the snow. I give the dealer and the service tech a little benefit of the doubt without more info. But I do not need the info, that is for you to investigate if so inclined, in a proper manor, rather than post a set of assumptions before actually talking to someone.