Wade might be overplaying the existence of the furin cleavage site. Derek Lowe, who writes the excellent In The Pipeline pharma blog I’ve linked a few times, says this:
I’ll eventually have to write about this. I think Wade overestimates the “smoking gun” potential of the furin cleavage site, but on the other hand the lab-escape theory is definitely still on the table. And the actions of the Chinese government are doing nothing to take it off.
Wade wrote this:
Viruses have all kinds of clever tricks, so why does the furin cleavage site stand out? Because of all known SARS-related beta-coronaviruses, only SARS2 possesses a furin cleavage site. All the other viruses have their S2 unit cleaved at a different site and by a different mechanism.
But this is carefully phrased. No other “SARS related” beta-coronaviruses have the site, but other beta-coronaviruses do. There’s an article here which has them occurring independently in the genomes of various branches of the coronavirus tree.
https://www.sciencedirect.com/science/article/pii/S1873506120304165
This means the virus could have acquired it via recombination while circulating in bats. Wade also asserts that SARS2 is poorly transmitted in bats but this assertion also seems suspect, as this article has several bat species susceptible to it.