Thanks! looks like it was a screwup by the ycombinator.com software. The original link ends with a period, and the software stripped it out -- probably because adding a period after a link that is at the end of a sentence is a common error.
I replaced it with another page on Wikipedia that redirects to the "User:Guy Macon/Yes. We are biased." page.
Full disclosure: I am the author of the Wikipedia essay "Wikipedia has cancer".