YIKES!!! Excuse the, all caps, but that is horrible and sad. As (I hope) most people are aware of, even the elderly experience some kind of mistreatment, (in this case, I think was a form of bullying) some worse than others. Sorry, that you and your Dad had to deal with that.
In Canada, people with disabilities (like myself) and the elderly need to be treated better. I don't have it that bad (as I still live at home) but in a care home near where I live, there are four beds in I assume most rooms there and my Mom was visiting someone there, and she due to the 'bed issue' my Mom had to sit on that person's bed, even though she didn't want to.
A friend of mine who is literally a few days younger than me is severely disabled and the care home she lives in, serves questionable food, once she got sent to the hospital in another city as they didn't properly cut up the food well enough, so the food got trapped in her throat so a surgeon had to take the food out. Also, my friend is forced to wear a diaper instead of getting the help she needs to 'use the washroom'. Nurses and care workers need to do more with people with special needs and the elderly and not be lazy. I know it is hard work, to care for the needy, but that is no excuse to be lazy. People need to care more about others.
I know it isn't your Dad's situation, but they are other areas that staff and others need to work on with the elderly and persons with disabilities.