Sorry Tiger, I think this is dis-information coming out of China's state security apparatus; attempting to reinforce the geopolitical spin that China is really honestly working with U.S. and S.Korea on this issue. I don't buy it.
I know they are belatedly bitching about it, and trying to deflect its responsibility for this "disaster."
What I am wondering about is whether N. Korea back-stabbed China regarding the nuclear test.
To me, it is quite plausible that N. Korea goes freelancing, jerks around China a bit, and even plays Russia against China. N. Koreans are certainly capable of this.
I agree with you on the point that Chinese are not honestly working with U.S. nor S. Korea. However, they could have been duped by N. Korea, feeling that they have N. Korea "under control."