Patrick, I see your point, but then I have this question: if those companies don't care about the terms of the GPL, why would they care if they are banned from using the software altogether? They would use it anyway. If you couldn't bring them to court for violating the GPL, what makes you think you could bring them to court for using your software?
Also, it's a double-edged sword, because some of those companies don't care about proprietary licenses (or copyright or trademarks in general) as well. And I bet proprietary developers are a lot more annoyed than we can be, and equally unable to do anything about it. But there's a lot of good free software coming out from China, especially Hong Kong. There are some high-profile libre projects that are developed in China (Gogs and Cocos2D-X, IIRC). I think it wouldn't be fair to discriminate against all Chinese developers just because of a few bad apples (which also exist in the West, by the way).
