This was very much expected as China has strict financial liquidity controls and bitcoin was being used expressly to bypass the same and take money out of the system. The Chinese government isn't stupid.
If yuan are hard to spend, due to legal constraints, I don't imagine a non-Chines is willing to sell BTC for yuan.
How would a Chinese use BTC in this way? Buy BTC from someone willing to accept yuan; spend the BTC on .... foreign goods mailed to China? Foreign assets, to "park" the value for a while ?