And really, he has no idea what's going to happen to those slides, who else will see them, or what misconstrued message may come across in the absence of the talk itself.
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.
Consider: would Apple ever release a Jobs Keynote with slides-only. Not likely. The alternative they provide is to make the entire presentation (or select portions) available as complete AV presentations (QT or whatever).