Because he did not wanted to delete genuine messages? Though it says the wiki has been largely not active, but it seems he wanted to restore it's functionality (he also started requiring a password for making edits now).
This was supposed to take 2 weeks of manual work, I took a look at it, googled how to do it automatically, finished the whole thing in a few minutes.
But both this assistant and the PhD they reported to were ready to spend 2 weeks doing it manually.
"I wanted to live deep and suck out all the marrow of life, to live so sturdily and Spartan-like as to put to rout all that was not life, to cut a broad swath and shave close, to drive life into a corner, and reduce it to its lowest terms, and, if it proved to be mean, why then to get the whole and genuine meanness of it, and publish its meanness to the world; or if it were sublime, to know it by experience, and be able to give a true account of it in my next excursion."