If it’s styrofoam we are talking a couple pounds. If that’s going to stress the door and opener then they are garbage. There is a process to insulate non insulated doors, granted it’s no where near as good as a real insulated door, there are kits and it’s a thing.

If the company though holding the warranty hostage over it then reality didn’t really matter but what the service provider wants. I assume they want to sell you something.