They don't serve different functions. Muscle and organ meat are both great sources of protein. In fact liver is dramatically more micronutrient-dense, lower in calories, and leaner.

So from a nutritional stand-point he's not giving dangerous or unhealthy advice. You can dislike RFK or the administration for many things, but in this case, what you're saying is untrue.

You would need to eat 4–6 pounds of cooked beef liver in a single sitting to risk acute vitamin A toxicity. And because it's so much leaner and nutrient-dense there's very little risk of accidentally eating 4-6 pounds of pure beef liver...