I'm inclined to agree with you based on my political views, but in this case.... Chinese were pretty reserved about outsiders meddling in their internal affairs already before Covid, so this isn't necessarily indicative.

China has claimed that COVID started in anywhere but China.

Australia: https://www.dailymail.co.uk/news/article-9024311/China-claim...

India: https://www.dailymail.co.uk/news/article-8993667/Now-Chinese...

Italy: https://www.the-sun.com/news/1824950/china-accuses-italy-sta...

US Army: https://www.msn.com/en-us/news/world/china-claims-that-the-u...

Since the common belief is that COVID originated in China, they stand to benefit from an independent inquiry that proves any of their above claims.

Here is a new article from the Associated Press "China clamps down in hidden hunt for coronavirus origins".

https://apnews.com/article/united-nations-coronavirus-pandem...

How would they benefit?

I don't think that's a strong indicator. Why would you want an investigation that likely requires you to grant foreign investigators access to your bioweapon labs and their records?