I think the reason is that the Chinese government doesn't care as much about the danger to humanity as they do about saving face and maintaining their power.
They may even know definitively where it came from, whether it was a lab with lax safety practices or from reckless agriculture. And they can fix either or both of those things, quietly, while still pushing the narrative internally that the virus didn't come from China at all.
I agree, and I'm interested to watch e.g. whether the WIV continues to publish risky research. My private guess is a paper or two for the sake of appearances, but a much lower volume of sampling and lab manipulation of novel pathogens than before--the CCP doesn't want to lose face, but it doesn't want another pandemic either.
It sure would be nice to know what happened, though, both for the sake of human knowledge and to inform similar research (or agriculture, or whatever else might have caused this) outside China. I don't what it's possible to learn given the delay and CCP's obstruction, but it seems defeatist not to try.
They may even know definitively where it came from, whether it was a lab with lax safety practices or from reckless agriculture. And they can fix either or both of those things, quietly, while still pushing the narrative internally that the virus didn't come from China at all.