Tough. Then maybe he shouldn't give talks. Who knows how they may be misinterpreted, even while he gives the talk!

Communication is an uncertain art. You never know what people are going to do with what you tell them, even if they do get it clearly. If you don't want to take that risk, just don't give talks. If you want to play this game, though, maintaining an illusion that you have some kind of control over the ideas you're presenting once they've left your mind and turned into some kind of transmissible form (be it talking, slides, or interpretive dance) is downright false.