It's too bad the groomer's deemed him unwashable. Had he been to where I work we probably would have muzzled him and tried to clean his ears then. If he had freaked out still, we would have just left his ears alone and continued with his bath. I've been working at a grooming shop for almost 3 years and I've never seen a dog be turned away, although we have gotten dogs that have been turned away from other places.
It's good to know you are working on his issues. You are a dedicated dog parent

Maybe some of Twisterdog's suggestions would work for you. Or maybe you could find a do it yourself place where you can take the dog in and bath it yourself and they clean up the mess.

Good luck!!