The ad revenue estimate could be off by as much as an order of magnitude. This is a non-story. There are millions of spam websites on the internet.
Unlike most spam websites, this one actually provides a useful and helpful function. The next time I 404 on a PDF I'll be sure to search for it on this site.
Meanwhile this website is actually an "honest" one that works for the visitors as advertised! I think it would be great injustice by selectively just enforcing the copyright laws by seizing this individual websites and its income. After all, 30% of the websites on the entire Internet are like this. I don't think the blog post really have a point.