I'd add:

3. Experts who conduct or fund virology research don't want it to be true, because it would inevitably cause a massive clampdown on what research is allowed and how it is conducted. It would also cause lasting damage to the field's reputation and prestige. Eg. imagine being a nuclear researcher in the aftermath of Chernobyl.

4. People who have significant personal or business ties with China are concerned that a finding of culpability will result in escalating tariffs and other sanctions, damaging China's economy and potentially causing collateral damage for those who do business with Chinese firms.