My bet is that even in China (which is not monolithic) different stakeholders are not so sure and there's major CYA between the scientists, the local managers, the Beijing-based leadership, senior leadership at all levels. Nothing good can come for any of these people if they allow the investigation to proceed smoothly. What if it's discovered that some totally unrelated incident happened years ago or that somebody was embezzling or did shady land deals with Wuhan lab accounts? The truth only helps people who are not involved. Everybody involved is best served by keeping their mouth shut and blocking any investigation.