if you care, email Rich, the author, and ask that he remove the apostrophe. no one here needs to be made aware of your nitpicking.
Truth to tell, I looked at the article for contact information—obviously far too cursorily—and, when I didn't see it, figured that the author would be likely to spot it on Hacker News. (I have since e-mailed the author.)
(You were right in either case, apparently.)