Facebook to sue Xiaonei next?

According to Financial Times, Facebook is filing a law suit against German facebook clone StudiVZ. There is some coverage in Insidefacebook and Techcrunch.

The interesting question brought up by Insidefacebook is that, will facebook sue the Chinese clone Xiaonei next? Clearly, in terms of clone, Xiaonei is a better one. There is even no "replacing Facebook’s blue colour scheme with a red one".
The question is, why didn't facebook sue xiaonei first? My guess is that, first, China's copyright law isn't as perfect as US, so maybe facebook doesn't want to get itself in trouble. Second, there is rumor saying that facebook has been blocked in China, due to it's highly opened platform and potential sensitive information. It doesn't sound like a good idea to mess with it by suing a Chinese competitor. Google and Baidu's battle could be a good example. Pretty much everyone agreed that Baidu plays an important role in the block of Google back to several years ago. Third, Xiaonei do have some features designed for Chinese market that facebook doesn't have, so maybe legally it's a little harder to approach the lay suit.

If like people said, you should always sue where the money is, Xiaonei is definitely a better option. They have raised $430 million this year, which seems a bigger number than StudiVZ's price(€100M). So it's likely Xiaonei will be the next target.

Or, maybe here facebook is sending a message to the rest clones: behave, otherwise I'm gonna go after you. Or...will facebook deal with it by acquiring Xiaonei? well...just a wild guess.