Why this weird insistence here on Slashdot that the lab leak theory is somehow a "conspiracy theory" or a "right-wing talking point?"
Because we are skeptics and it is a conspiracy theory.
Does that not give the NIH an incentive to deflect attention away from the Wuhan Institute of Virology?
Well, maybe it gives them a very weak incentive. NIH is in no way responsible for how people in China might have used their money.
Also, this ridiculously tenuous link does not motivate the CIA to lie.
a false "grassroot" letter
The popularity of a theory or astroturfing about it has nothing to do with with its truthfulness.
HIGHLY unusual furin cleavage site in the virus
Unusual mutations happen all the time. That's how evolution has always worked.
the closest site where you find a potential bat species is a thousand miles away from the wetmarket.
Bats can fly. Also, nobody checked all the bats in Wuhan, including the dead and rotten ones.
You'd expect to find multiple infections along the path, or at the very least an infected animal somewhere,
You would not expect to "find" infections "along the path." First, nobody is systematically checking animals for viruses on the scale needed to find a "path." Second, the evidence biodegraded months before the investigations began. Third, experience shows that if you find a "link" along the path, conspiracy theorists will simply say that there are now two paths where nothing has been found; one before the link and one after. Fourth, transmission between animals has been extensively proven.
As a conclusion: Zoonotic infections are normal and have occurred frequently for a long time. Zoonotic infection is a simple theory. Simple theories that have been correct in the past are usually correct again.