Sounds like you are better informed than the physician assistant. You are correct that he is teaching an unhealthy diet to people, especially to people with diabetes who may be more harmed by the ketogenic diet you describe. It reminds me of the outdated high protein, low carbohydrate diets.
You can provide the web address to my low carbohydrate diets topic to the physician assistant and suggest he talk with the hospital dietitians in your healthcare facility. The dietitians can also set up a meeting to talk with the doctor to whom this physician assistant reports to provide nutrition therapy.
Forty-four states require licensure for persons providing nutrition therapy, especially in healthcare facilities. While doctors are covered under licensure laws, I am not sure a physician assistant would be depending on the state in which you live. Unfortunately, many people who recommend various weight loss diets have never taken a course in nutrition therapy and may not understand the body’s biochemical processes.