You should've also searched for the URL since people often post things as bare URLs. In any case, it would not have helped: neither Google nor LW/Reddit match search queries on embedded URLs. (Google used to support something like that, a link: operator, but the current results are so incomplete and bad I never bother any more.)

In this case, I knew we had already discussed the essay since I had found it interesting and I just went through "scurvy site:lesswrong.com" until I found the conversations.