I believe I read in one of their posts that they were XRV tires which would make them Motorcoach tires, not commercial truck tires.
XRV tires are designed for a softer ride on coaches. The Entegra is a big heavy coach, so it does not surprise me if the pressure is 120 psi.
But we also have to remember that Michelin had a bad reputation a few years back with XRV tires blowing up. That was one of the reasons why I got rid of my Michelin tires which were XRV.
Now as to the OP blaming Coach Net for refusing to go to the aid of the gentleman with the blow out. I believe that IF I was the owner of the coach I would have asked why, and after the explanation was given I would have called CW and asked them where and who was responsible for repairing the damage caused by the tire which had just left their grounds. I am sure that CW would have told them who would go pick up their coach and take it where it could be repaired.
But I believe the owner understandably was a little excited with the accident of the blowout and damage, and got very upset when Coach Net told him he had to go through CW's insurance or roadside service.