I have no confirmed information about this (and I think china financial discussion forums have more details) but I think the limitations are to BTC exchangers in general (the ones with banks and maybe registered) not just BTCChina.
Surely, like in the UK, the only regulation could possibly be around BTC exchanges (the funnels between Bitcoin and Fiat). They can't stop people from using it, but I can see why it would hurt the bitcoin economy if people aren't allowed to cash back out to fiat. If only because companies wouldn't adopt it. A company would only adopt it if their whole supply chain adopted it.