My question is, why? What does it matter whether the virus originated from a lab or from a wet market - it isn't any more dangerous if it came from a lab, nor does knowing the origin really help dealing with this crisis at all.
It is certainly interesting to know where it did originate, and that knowledge could inform a debate on the future of (respectively) wet markets and animal husbandry practices, or BSL facilities, but these don't strike me as particularly emotionally charged topics, and in any case the posts I'm referring to don't mention these debates...
Anybody care to explain why you would respond so strongly to claims of lab origin?
Throw some confirmation bias on top of it. The easiest group to blame for bad things is the group you already disliked. Traditionally this means foreigners, other races, and heretics. Blaming China both let's people have their imagined just world and vindicates whatever pre-existing hard-line stance they had on China. It's no secret that a lot of people already had a hard-lie stance on China for unrelated reasons (Eg the trade war).
In conclusion the human logical apparatus is bugged, no one is releasing any patches, and the whole issue is emotional because who you blame is tribal signaling dressed up as rational interest.