1. There are no absolute sales figures here. It may be that the game sold dismally and a story about piracy might have gotten them developer a ton more PR than the game ever would've;
2. The issue in this particular case is not number of copies (pirated vs non-pirated) but the amount of hours spent from pirated vs non-pirated. Even that doesn't tell the whole story. Perhaps this game required a critical mass of users (some do)? If so, pirated users might ultimately be beneficial.
Also, when it comes to piracy there are a lot of people who download a lot of pirated content and then never look at it or they might try it once. Just getting the pirated content itself becomes a game;
3. How expensive is it to maintain a server on a per user or per user hour basis anyway? It seems quite likely a single machine can serve thousands if not tens of thousands of users as a conservative estimate; and
4. Are they shuttering the game or just overhauling the authentication model? If they plan on rereleasing it then the publicity of (1) becomes even more likely.
Like I said, I've seen a number of one-sided stories now where I've known something about the other side and as sympathetic as someone can make their case, believe me--generally speaking--there is a lot they don't tell you.
Also, don't discount the possibility of internal politics. It's a lot easier for a product lead to say "we had to pull this because of piracy" to his or her boss or board than it is to say "we made a game that no one bought".
I'm just saying.