Point taken on "original", and thanks for updating the article! Gwern has also found a link on the HP homepage.

What I wanted was to show the quote in question - to make it available to the reader of my post so they could check that I had my facts right. For that purpose the link is what I really needed, not "merely" a citation; and it sucks that the link went dead, but that wasn't under my control.

I'm not saying you shouldn't have given the link -- I'm saying that if you had also given the citation, then even after the link broke, it would have been slightly more inconvenient but not difficult for me to look it up! That's the main point of also giving the citation: to make the source available to the reader of your post even if the link rots.