I'm gonna try and ignore most of this post and just say that viruses make a pretty shit weapon, because you can't control them. So unless you're thinking of Bond villain-like plans, I fail to see how this could benefit China.I don't believe a word of this "it started in a outdoor food market" story.
Why is it that these viruses always start in China? SARS, avian bird flu, both started there. It is all too much of a coincidence.
Stuff like this doesn't leak from a laboratory - much more likely that these viruses are man-made and were being deliberately released as a means of testing the virus on the chinese population.
Wars are expensive - much cheaper if you can kill off a few million people in a couple of months with a biological weapon and destabilise a country.
And China has been known to be likely to birth new strands of viruses because it's the meeting point of a lot of migratory bird routes and it has large bodies of stagnant water + intensive farms of pigs and poultry, not to mention the hygiene/health danger awareness among the lowest classes isn't always great.