My shih tzu pepper is a rescue baby. She was badly matted. We shaved her down and I don't see how you can hurt her because they have the guards. Her hair is kept short. Her face has a puppy cut so she can see very well. I just do it myself.
I neglected to mention that our shih tzu, Stanley, really likes to be groomed. When he sees me getting the grooming stuff out he runs right over and tries to climb on the table. I just can't get his face.
Go get him a close cut, sometimes the groomer can work with it and leave it a bit longer then skin close. If you want the dog to be longer its up to you to get the dog brushed out everyday, and the groomer should groom it every 6 weeks. Its very important to never bath a matted dog or the knots will just get tighter. Also bathing a dog and then the dog rolling around alot will just mat up the dog. If you want to bath the dog, scrub in one direction, not circles. Always brush out the dog before the bath. And comepletely dry the dog before you let it go.
Saying you're going to put this groomer out of business is a little tacky. Probably impossible as well, my dad was the mayor for 16 years.. and never tried to shut anybody down because they scared his dog. That is ridiculous. lol. Let it go, and take your dog to somebody else. Simply.