That may be
but that doesn't mean that he's not being satirical. It only means that those students are as deaf to satire as the author is.
Let me put it another way. In one sense, he's completely right; if you want to maintain ecological systems in their current form, one needs to reduce the impact of human beings on them by some metric; he's chosen 90% (evidence for his number is another discussion). What's the easiest way to achieve that? Get rid of 90% of the humans. What's the easiest way to achieve that? Use disease to do so.
Don't forget that his training is in ecology, one of the large tenets of which is that ecological systems (including the environment in which they reside) use feedback mechanisms to maintain the suitability for itself in its environment. Simply put, the disease need not arise from human agency; it could be the result of a feedback mechanism deciding that it has to make the environment less suitable for human beings. Assuming that human agency is the only possible source for such an actor as a disease is arrogance and/or speciecentrism. As for the use of the example of ebola, that is where you step into the realm of satire; selecting the nastiest possible agent to effect the change. I suspect his real point is that (esp. at Western levels of consumption) we need to find a way to reduce our impacts by ~90% if we wish to maintain a good world for our descendents. Sometimes satire is one of the better way to get this point across: c.f. A Modest Proposal. After all, the central point of A Modest Proposal is that what the English landowners were doing to the Irish was functionally identical to treating Irish children as meat animals.
One of the central tenets of honourable debate is called Charity: when there are several possible interpretations of a statement, one should take the most charitable one; this is somewhat similar in concept to Occam's Razor. I have presented a far more charitable reading of the point of the speech, and one that fits the facts as we know them. Furthermore, it fits with the kind of awareness of the culture and of forms of storytelling that someone of Pianka's age and experience would have. One of the big problems we've been having in North America's ongoing political discourse is a serious inversion of the principle of charity (i.e. take the worst possible interpretation of an opponent's viewpoint, and use it as a stick to beat up on them so as to help convince third parties of the Rightness Of My Way), and to me this looks like a very good example of this inversion.
--\n-------------------------------------------------------------------\n* Jack Troughton jake at consultron.ca *\n* [link|http://consultron.ca|http://consultron.ca] [link|irc://irc.ecomstation.ca|irc://irc.ecomstation.ca] *\n* Kingston Ontario Canada [link|news://news.consultron.ca|news://news.consultron.ca] *\n-------------------------------------------------------------------
