Look: Do I believe the official Chinese version, about anything? No of course not, and that includes COVID, infrastructure, road and belt targets, etc.
Meanwhile: That’s kind of par for the point-of-origin quest cycle in non-allied nations – no one likes to have foreign envoys roaming within their borders.
Saudi Arabia has been less transparent with MERS, and that was for a small number of cases.
Does China’s lack of transparency inspire confidence? Obviously not. Should we jump to conclusions automatically because they don’t want to submit to voluntary inquiry? I don’t see any incentive for them to do that, and so I don’t see any reason to read this as anything else you would expect them to do.