Adding a comment made by Bill Lagokos in an old interview found while cleaning out of podcasts: He thinks this concern about "too much protein" when trying to stay in ketosis arises from the diets used with epileptic children. They need enough calories to grow while restricting carbs. If they ate too much protein, they wouldn't have the appetite to eat enough fat and calories and grow, leading to the strict protein formulas seen in their studies.
Which brings us back to Dr Fung's flexible protein guidelines of 20-30% of calories for us old folks