The assumption that there are no fans at cons who don't want to be (professional) authors irritates me, but that may not be what that panelist was thinking. He may have figured that the audience for that panel was aspiring authors who were treating it as some combination of manual and warning label, in the same way that panels on how to find an agent aren't going to have a wide audience of non-authors, even if we'd happily listen to the same panelists talk about alternate history, current space exploration, or the writing of that year's GoH.