Because they thought they had accidentally released a virus from their Biowar experiments (See "Gain-of-Function") into their general population. As indeed they most likely did.
And all the other Governments wound up getting that same information eventually. But nobody wants to start a war over this little "oops". The oligarchies running all major counties have too much to lose. So - "it was the Wuhan Seafood Market as the source". "Just one of those things".
It is heartening to realize that Government bureaucrats across the world universally tend to exaggerate progress reports on major programs. COVID-19 is more infectious, but less lethal than expected, and continues evolving in that direction. Also, a lot of very smart people are discovering various treatments that seem effective.
We are gonna be OK. Well, most of us anyway.
I agree with your take that it accidentally escaped from the lab near the market. Also, that this research had obvious bio-war applications. And further, that a war wouldn’t fix any thing for anyone.
And, in case it happens again, the live market is still there to blame.
One question I still have is why Fauci (and for that matter the labs at UNC and in Canada) were dumb enough to be sharing this research with the Chinese. Sure, there’s a ready answer in that all knowledge is good, and we were cooperating with them. But the Chinese interest in biowarfare was well known, and accidents have happened at various times with this sort of research (a Russian anthrax escape comes to mind).