I'm not sure if you agree with me or not! He knows he strength is not about the facts or plan etc. He's strength is to argue period. Take away his strength. If he can't argue with you then he needs to answer the question asked of him. That's his weakness!
He's not going to do that and he's not interested in that. You don't need to argue in order to hit back. You need to guide him. Meaning don't go off course with him, jab him with relevant words off script that bring home the point of the question the moderator asked.