In some conferences this might have been more harmful to his business. However, he was promoting a viral marketing company using creative marketing tactics to a group of jaded marketers. At the worst they would see it as more spam. Or his highly-targeted audience, having already expressed an interest in his service by attending the session led by a competitor, would respond to his bottom-line appeal. A classic example of differentiation.

His audience was probably more receptive to this than non-marketers would have been. And certainly this appeal wouldn't have been successful if the entire conference was about his competitor. But this was a large and varied marketing conference. As he says, know your audience and market accordingly.