I think without knowing exactly what the groomer said and how he said it, it is tough to debate here. I absolutely love my groomer, he is the most gentle man I have ever met. I have brought each of my dogs to him before they were fully trained and while no biting, I am sure they were not easy. I think groomers can probably have a gentle discussion and give referrals as a way of saying it nicely? Or at least I am going to hope so
I understand everything you are saying, but there is always a choice to be empathetic and offer resources.