- Most high-end virology labs are doing research on human to human transmission of corona viruses. They're a major emerging type of virus we don't understand, and a Chinese lab working on them is even less surprising.
- If this was a bioweapon, it sucks.
Like, can you spin the theory that we're missing them? Sure. But there's a pretty strong absence of evidence there, despite a field that's actively looking constantly (and where showing that would further the political and scientific careers of a number of people).
Bioweapons aren't all that effective in general for the reasons seen here: they're too slowly acting, to easy to treat, and not as lethal as, say, chemical weapons (which are also not that effective as weapons). Biological weapons are most dangerous as terror weapons.
I hate to say anything more, because we would easily move into wild speculation territory.
But this was mostly to address the terminal version of this particular rumor, which I've also encountered on social media.