Who said this? You? Or are you claiming that Dr. Cabaj extrapolated 10,000 out of 40,000? Please provide your cite.
Dr. Cabaj estimated twenty-five percent of all newly infected gay men, not twenty-five percent of all new infections.
The link at the top of this page clearly goes back to Andrew Sullivan's web site. I am not Andrew Sullivan, so no, I did not say any of this. If you read what was posted, you would have noticed this "The piece is not online, but the precis reads like Stephen Glass". That's clearly where the quote is from. Sullivan hasn't linked to it because it isn't online, or at least, he doesn't know where it appears online.