I also feel like if he's serious about it, he would produce something other than a tweet thread, at least a real blog post with links to papers he refers to. Otherwise it's hard for me to take them any more seriously than anyone else who handwaves about papers.
It would be nice to see something like that with good faith opportunities for people to respond and counterrespond but I'm skeptical about it happening.
There's also a sense that I have from reading stuff like that and others that we should treat the peer-reviewed academic paper trail as somehow the state of things, rather than looking at the evidence on its own terms. I don't mean anything conspiratorial about that, just that it's almost like they expect there to be some peer-reviewed paper out there from China that shows how they would have engineered it if they had, as if that's realistic at all.
That's not even getting into what you mention, which is the possibility nothing was engineered and there was a leak.