I'm afraid my dad will get my mother kicked out of a nursing home.

Well your dad is on the job. Taking care of his wife. Does your dad have dementia? Anxiety? Does he spend all day with your mom? Perhaps he needs to take a break from sitting with your mom to give him some perspective. My MIL was in rehab for a short while after a hospitalization. FIL would go and sit in her room all day. She was in a semiprivate room. FIL kept adjusting the temperature. The room mate was very kind. Everyone else kept telling him to leave the thermostat alone, including the nurses. He would say, the room is too cold, it makes my nose run. Indeed it did. It was totally lost on him that his comfort wasn't of concern. That he wasn't a patient. That he could go home. Thankfully MIL wasn't in the rehab long. I can't imagine your dad being there everyday for the duration. I have no idea how much a NH will put up with. I suspect it's common for the spouse to be there. Perhaps you should speak with someone at the NH to see what they suggest before it goes too far. I'm sure your dad wants to be with her. I know it's stressful for you. At least you know where he is and what he's doing. Wish I knew how to help. With my In laws, it would have been a big problem too. They both passed before they reached this stage. Let us know how it goes.

I gyess there is a fine line between "argueing" and "advocating". Does the staff have your mom on a toileting schedule, or are they saying she should be considered incontinent and in diapers? And is she being changed regularly? Has a doctor scripted PT that's not being done? Is mom able to participate in pt? Follow instructions?

Look, Dad is afraid of losing your mom, and grieving. Is he recieving help from a social worker or counselor? Is HE experiencing cognitive decline?

I'm just trying to look at this from his viewpoint.

Yes, they could. Has your dad talked to a social worker? Have you encouraged him to stop this behavior? Probably worse than telling mom she had to leave was if they told your dad that he could no longer visit mom.

Your dad needs to control himself. His behavior could be impacting mom's care, no that would not be right, and behaviors. He is not helping mom by being so vocal. If he wants better care for mom he needs to back off. I am sure the staff at NH tries to avoid him at all costs.