I haven't watched it eh... yet. Does he say that Ondra would do 10a if he stopped eating mostly veggies and started to eat butter instead?
I skipped through bits and landed on him saying the exact opposite. He suspects many people and particularly those with elite genetics like ondra would perform worse on keto, but there are a smaller percentage of people who would do better, himself being one. (He who dares might win?)
Also, his keto diet has 50-100g carbs daily, whilst still having the right level of ketones in the blood, so it would include about as much fibrous veg as you'd ever want really.
I probably saw about 30 min worth of him talking overall and it all seemed relatively reasonable. Still, I'm already happy with a non keto diet myself.