1996 Jeep Cherokee Answers for differential going out often

Drive Train Axles Bearings problem
1996 Jeep Cherokee All Wheel Drive Automatic

some time back you posted this answer in response to a guy frustrated that his front diff went out frequently after putting new tires on the front making a half inch difference to the back. The dealer held him liable. Here is what you said.
"Answer: We cannot conceive that the 1/2-inch difference in the circumference of the tires would cause the differential to fail. Moreover, it is extremely rare to have a differential fail after 200 miles. It would appear from our perspective and based on what you have told us that the repairs were incorrectly done. "

I cannot believe that you would say such a thing. This vehicle is an all wheel drive vehicle which means it is locked into 4 wheel drive at all times. It has a viscous coupling between the front and rear axles. Jeep documentation says that same tire sizes are extremely important and incorrectly sized tires could cause catastrophic failure of the viscous coupling.
Having even 1/2 inch difference from front to rear is going to cause extreme tire wear, heat from the viscous coupling causing it to fail, and constant extreme pressure on the front differential gears. This cars mileage would also suffer since the drive train is constantly bound up.
Your contradiction of the dealers right on answer is not very helpful. You did apologize and give the man his money back?