Yes, I have seen it.
I am an MD. No, I am not a neurologist. I supervise and teach them, have taught neurology board certification, including neuro critical care subspecialty boards.
It does not require a neurologist for diagnosis. I would be more confident with a neurologist diagnosis.
It sounds like you, or your friend, might doubt the diagnosis.
Age related changes likely contribute. With a true repetitive motion injury, the only true solution is to stop doing whatever is creating the problem.
The classic: It hurts when I do this. Don't do that.
I would hate to see a person lose the social interaction and physical activity. Likely that could contribute to age related decline.
There is the matter of tolerance. If one can moderate the activity, and tolerate the discomfort, a happy medium might be reached. Best to work with one's doctor on that. It is key to avoid exacerbation of the injury. Avoiding chronic use of medications to deal with it can be important as well.
Of course, you can always just ask in a pool forum and get a clown to respond. LOL!