If he felt so strongly about preventing others wasting time then wouldn't he have been better putting them forward in a diplomatic way that didn't embarrass the

If he felt so strongly about preventing others wasting time then wouldn't he have been better putting them forward in a diplomatic way that didn't embarrass the presenter (who was as a result likely to be defensive and therefore unlikely to learn) and alienate some members of the audience (and who now think he's a dick and are probably less likely to learn from him)? Yehuda's approach if accurately described was as much about being right as about others learning. Confrontation is rarely a good teaching technique so I'm not clear why you justify his behaviour as in some way enhancing that goal.