Why? Because it seems like US institutions and people (right up to Fauci) were involved in this research and may not want the domestic blowback.
Conveniently the CCP don't want a paper trail either.
I'd be pretty sure the various scenarios have already been gamed out in both countries.
Edit: Not sure why this is being downvoted, but just in case it’s a reflex because I mentioned Fauci: yes, he was head of NIAID, and yes, the NIH did fund this type of research at the WIV. The grants are public information.
Part 1, from 2014-2019, for 3.7M:
https://reporter.nih.gov/project-details/8674931
Part 2, from 2019 until it was cancelled in April 2020:
https://reporter.nih.gov/project-details/9819304
Both led by Peter Daszak who is now also the lead WHO investigator. The same person who decided the WHO didn’t need to see the deleted virus databases, and the same person who co-ordinated the Lancet statement which minimised the lab leak theory early on (and let to it being considered a conspiracy theory).
Here he is on This Week In Virology, describing this sort of work. It’s worth watching the whole thing, but gets most interesting from minute 27 onward:
https://m.youtube.com/watch?v=IdYDL_RK--w
For example he confirms it’s easy to modify these viruses in the lab, and mentions collaborating with Ralph Baric at UNC. Baric invented Remdesivir (with Gilead) - the “cure” that turned out not to work very well. His lab was doing gain of function experiments before the ban. Shi Zhengli (“bat woman” from Wuhan) worked very closely with Baric and Daszak.
https://www.newsweek.com/dr-fauci-backed-controversial-wuhan...