The Seguin Gazette-Enterprise has been pulling their transcripts of the story. Fortunately, it's cached. Hardly surprising, it turns out their 'source', Forrest Mims, was a regular writer for the paper.
On top of that your first link has this in it.... On March 31, Dr. Pianka spoke to students and parents at St. Edwards University in Austin, Texas. "A University of Texas professor says the Earth would be better off with 90 percent of the human population dead," is how the Gazette-Enterprise led its coverage of the talk.
Uh huh. And now the paper has pulled the transcript that would allow us to check.
Where's the skepticism of the media, here, Andrew? Even the New York Times doesn't consign stories to the memory hole. (Hope that reference is not over your head). Whart kind of 'newspaper' attempts to eliminate its own news stories when they are questioned?
What you have is second hand accounts from compromised sources. And now they're being destroyed by the people who wrote them.
And you have no sources. And I do have a primary source, the good professor's own webpage. He is the one that posted a comment made 2 years ago which mentions an opinion nearly exact to his opinion allegedly(by multiple independent sources) spoken last month. In addition, comments such as "Allan Hook, a St. Edward's biology professor who heard both speeches, said Dr. Pianka "wasn't so perhaps adamant in his own personal views of what he thinks might happen" in his second lecture." add weight to the allegations.