That's complete FUD on several levels. On a most general level, mining itself only needs the header. Chinese miners can verify blocks and transactions elsewhere and only send headers to the actual mining sites. A dial-up should be enough.

Regardless, from what I heard it's not a problem anymore. Even if it was, allowing 'fast passage' for bitcoin blocks seems like a obvious course of action for the Chinese government, it's just another export industry at this point.