They can still buy using bank deposits, just not with money via 3rd parties. Similarly okpay, dwolla and aurumxchange were all stamped on last year by regulators in the West.
This is my understanding as well. The banks may not partake in anything bitcoin. Payment processors are banned from doing business with any bitcoin exchange.
-but- I do not see any problems with banks wiring yuan to companies operating exchanges, yet.
My suspicion is that all the Chinese gov't really wants is to be able to watch and control the flow of their money, through the banks, and they're still loading up on gold as well.
My feeling is that they really don't understand what bitcoin means just yet, they are still focused on the currency wars going on in the "real world".
If bank deposits stop, it will drive it completely underground. I think they prefer to keep a watchful eye.