Hmmm, I am kind of wrestling with the same thing myself. This summer I took Ranger to our local training club and my daughter (14 yo) was the trainer (although I was present at every class). My daughter is extremely shy and I thought that a dog training class would be good for her, but the instructor was VERY hard on her. She was constantly telling my daughter that she was doing things wrong in a very unpleasant way. My daughter was speaking very softly to Ranger and praising him in a very soft voice and the instructor kept yelling at her that Ranger couldn't hear her. The really weird thing is that Ranger was probably doing the best of any of the dogs in the class. The instructor apologized to me (not my daughter) after the first class so we gave it another try. After the third class without any change in this behavior, I gave up and encouraged dd to stay home. The instructor was livid when ai showed up without dd. She had arranged for some kids to be at that class for dd to relate to. It was nice of her, but it was too late. I find it really funny that she was so into posotive reinforcement for the dogs but felt my shy 14 yo daughter would do better with negative training, LOL.
It never occured to me that Ranger being a GSD could have been part of the problem. All the other people and dogs in the class liked him. And they were really nice people. It is a pity that the instructor wasn't more welcoming.
So, I guess I wouldn't say anything. I think some of these people are just very set in their ways and you are not going to change them.