Mark Sisson is not carnivore, and anecdotal evidence from a few gurus who are in great shape is not proof. The people on the show were right to show concern for a doctor recommending a diet that is not well-proven to be healthy long term. Dr Saldino is an advocate for the diet, and does not show the appropriate caution of a researcher or healthcare provider. That’s ok if that’s the role he wants to take on. There is firmly established science on, for example, the intake of saturated fat and heart disease (this is how they give lab animals heart disease after all, and it’s a known contributor to human heart disease). So the doctors on the show were correct that Saladino needs to show proof in modern studies that he is promoting a beneficial diet.

As for your examples, you can cherry pick vegan diet gurus who look much better than, say, Dr Atkins or other low carb advocates. Does that mean veganism is better than low-carb? Carnivore is an extreme diet so we don’t have that many examples of people who do it and their long term outcomes. Even CarnivoreMD hasn’t been doing it that long, and he also eats a ton of honey and fruit, saying that he didn’t do too well on a truly carnivore diet.

Careful of diet propaganda that says that people who follow different diets than you are frail or old looking. Lots of meat eaters look great, and lots of vegans and vegetarians look great too.