Earlier quoted context omitted.
The cover up didn't need to be colossal, just for everyone to point to occams razor and call anyone with a hint of curiosity a racist. The fact that the origin of the outbreak appears to be in the same vicinity as a lab that experiments on similar viruses alone is sufficient reason to want a thorough investigation. Otherwise, the odds that nature produced such a virus, in such a location, make for a crazy coincidence…
We had SARS-1 crop up in Guangdong in 2003 when the nearest known related virus has been found in Yunnan some ~700 miles away. There just wasn't a lab there to leak from. This time it popped up about ~700 miles away again, but where there was a lab. The actual chances of that happening are probably about 1-in-10 / 1-in-20 if we understood the movement of people and animals within China that produced both outbreaks. T…
You present many reasonable arguments that natural origin is possible, and I agree that it is. That doesn't mean lab origin is impossible though, and it doesn't mean the possibility is negligible unless your prior is very heavily biased against it. Considering that a lab-origin pandemic has probably happened before (and has even been dismissed as clearly natural by the WHO[2], before the later scientific consensus corrected that!), I don't see where you're getting the confidence you've expressed in other comments that the origin of this one is certainly natural.
As to exact numbers, I agree that it's reasonable to consider only the urban population, since emergence would probably be in a city. There's no reason to limit the population to China, though--natural emergence elsewhere in SE Asia would also have been possible, and the WIV's research program is distinctive not just in China but in the world. It seems like our disagreement hinges mostly on that first prior (considering that a pandemic emerged, but no other information), though.
1. https://www.nejm.org/doi/full/10.1056/NEJMra0904322
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2395678/pdf/bul...