Nonsense. Eskimos, Okinawans, Turkish mountain people, Amazonian tribes, Europeans, Africans, Mediterraneans, etc, etc, all have radically different diets with varying levels of carbs, fat and protein. The common denominator for people who live long is how many calories they ingest. A person on a low calorie diet is simply healthier.
You are correct that drastically reducing calories, and fasting occasionally, is
one way to promote good health and longevity, even if those calories come from carbs. But you will lose muscle and have trouble gaining muscle.
If you are consuming a
very low calorie diet from carbs, then you aren't consuming many calories from carbs anyway. So that's probably why in this case carbs don't interfere with a very low calorie diet's ability to improve health and longevity.
Eating more than 150g carbs per day, overtime, will raise your triglycerides, develop insulin resistance and possibly diabetes, develop fatty liver, and increase your risk of developing many other health issues.
The same is not true when consuming more than 150g protein or more than 150g fat per day. Nutritional ketosis simulates fasting, without restricting calories.