I respectfully disagree with this. Nobody knows how it works, so why couldn’t it be a subconscious phenomenon which can be improved through autosuggestion? There are also different ways in which a stutter can develop. They’re not all the same, and some may benefit from other forms of treatment. Speech therapy doesn’t work for everyone, and there’s nothing wrong with trying alternative methods. I also don’t think he’s saying “it’s his fault” - he’s just talking about it in terms of behavioral conditioning.