First of all China isn't banning Bitcoin but shutting down the exchanges. The sole purpose of shutting down the exchanges is to offer only one medium for buying cryptocurrencies that would be the cryptocurrency that government wil be launching. Then Chinese trader need to convert fiat first in government backed cryptocurrency and then use that to buy other cryptocurrencies. So that government can keep a check on money supply.
This makes no sense.
Even now if somebody would go to a Chinese exchange they would have to deposit money via a traceable payment gateway.
Be it a bank transfer or whatever they use there.
Just inserting another step like a government controlled crypto won't make things easier.
Once the guy gets his funds into an exchange and convert them to bitcoins the government loses it's track.
How do you proceed after this? You know one person has bought 10 btc but he can clam he has lost them, he has been hacked he can go and file a complain at the police, good luck proving he still owns those coins.