More important than the fact that the majority of mining takes place in China is the fact that the majority of ASIC devices are manufactured by one company: BITMAIN, which is a Chinese company.

The restrictions on BTC in China are not necessarily because China doesn't see any benefit in BTC business, buy because the government wants to suppress any attempt to access the free Internet.  If a monopoly like BITMAIN is operating in China they will be more interested in controlling as much of the company's activities as possible rather than restricting BTC as a whole.