Elon Musk is many things, but a charismatic public speaker is not one of them.
My problem with his delivery wasn't the stuttering—I doubt most of us could speak any better than him in public—it was him interacting with randoms shouting in the crowd. It's cute once or twice but you couldn't hear what was being yelled so Elon's responses were often devoid of context.
He seems to be better just chatting and speaking what ever's on his mind but stumbles when he's trying to be on message.