Trainer continued holding dogs foot after yelping, got bit. Seeking advice.

We have a 6.5 month old puppy we adopted from a rescue when she was about 12 weeks old. We listened to our vet (which I now regret) and pretty much quarantined her until about 16 or 17 weeks until she had her shots. She's pretty reactive but it's definitely fear based. She doesn't resource guard and gets along fine with our cats. Her reactivity has gotten better, before she would bark at dogs across the street but now she doesnt. Shell very rarely let people pet her and mostly just barks at them, but calms a little when she sees me give them a treat to give her.

Anyways, shes on week 5 of a 6 week training program for puppies. She's definitely still reactive but has more advanced training than the other two in the class. Anyways, today, the trainer was practice grooming with the dogs to see how they'd react. Our dog is very comfortable with us touching anywhere on her as we always clean her butt and feet when she comes in from outside, meaning she gets those areas touched multiple times a day.

So the trainer would squeeze their paw and if they wined she'd continue squeezing and pretend to clip the nails and only let up when they calmed down. The two other dogs yelped but she kept squeezing and eventually they stopped and got rewarded. When it came to my dog, she did well at first and let the trainer cut a nail. She then had had enough and wanted to be done and tbe trainer kept holding her paw but instead of stopping she continued yelping and trying to get outof being held, eventually biting the trainers hand. There were about 3 or 4 visible little "dents" where you could see where the teeth went and one of the dent broke skin and the trainer bled. She said it was fine and played it off pretty well actually. Saying it's something she definitely needs work on but that since she's an aussie mix she's more likely to be reactive in that scenario since she was bred to heard sheep, she just needs to learn she can't do it to people.

I'm pretty shocked and taken off guard. Our puppy is reactive, as mentioned, but very sweet and submissive to my husband and I. I guess I just want to vent and see if anyone else has been in a similar scenario and ask if it gets better, is there hope for her? What are your thoughts of how the trainer continued holding my dogs paw even when she was visible not happy and trying to get away? I know nothing about training so I'm unsure if this is proper since I'm always under the impression to listen to animals body language and act accordingly. We will be getting our dog into reactive classes and paying for private sessions so that she is set up for success. I'm just anxious about the situation and would like some input.