>However, since we observed all notable SARS-CoV-2 features, including the optimized RBD and polybasic cleavage site, in related coronaviruses in nature, we do not believe that any type of laboratory-based scenario is plausible.
The fact that covid's features are found in nature seems a weak argument to disprove lab involvement.
On the other hand covid seems well adapted to humans which could have come about by serial passage in a lab. Perhaps they were doing something like in vivo characterisation of spillover risk as mentioned in Daszak's grant application for the WIV?
Or something like:
>We performed in vivo experiments in transgenic (human ACE2 expressing) mice and civets in 2018 and 2019 in the Institute’s biosafety laboratory. The viruses we used were bat SARSr-CoV close to SARS-CoV. (Shi Zhengli)
?