Now it appears that whatever damage could be done was, and China did block access to key information. I haven't seen anything to indicate it did come from the lab, or didn't. China's actions are consistent with either scenario. It would be very embarrassing to Chinese leadership if the lab-escape idea became popular, regardless of whether it was true, but especially if it were found to be true. China will be acting mainly to try to stop the idea gaining popularity, and be much less concerned with whether the international community actually learns its true origin.
But if the Chinese leadership had confidence that it escaped the lab, my interpretation is they would probably do a lot more stone-walling than they are doing. But that doesn't mean it didn't.
My brother flies freight in and out of Wuhan, never leaving the airport, and says border-patrol behavior at that airport is very strange, unlike at any other Chinese city. Before they are allowed to take off, the whole plane is carefully searched by soldiers in complete-isolation bunny suits, and passports collected on arrival are then carefully matched, one by one, to each crew member before departure. His interpretation is that China wants to be certain that nobody in Wuhan leaves China whom they would rather have stay.
What that would mean, if correct, I cannot guess.
Doctors have escaped and claimed that it was lab engineered
https://bgr.com/2020/09/15/coronavirus-whistleblower-wuhan-l...
The Chinese are much better at stonewalling than you give them credit for. Allowing a team into the country was a major concession, and getting to actually meet (some) lab employees, sheesh! That amounts to a charm offensive, in context.