Gain of function proponents are ignoring research that indicates it's not possible to generate a virus dangerous to humans without leaving specific telltales. While this study isn't necessarily conclusive or a door slam in the face of lab leak, it's pretty huge data point that makes it far less likely.
I also forgot to mention that he deliberately ignored the humanized mice being the location of the serial passage work, and straw manned a "petri dish". Completely misrepresenting the fact that was most crucial.
In the future, using a Twitter account with locked comments is inadvisable. He blocked comments for a reason.
His entire argument is very straightforward. Zoonotic origin is highly plausible, has caused previous SARS outbreaks, has no evidence against it. Lab leak is possible, though it has no precedent and there's evidence that makes it less likely. There's no conclusive evidence for either. The balance of evidence and history leans heavily to zoonotic. There is absolutely nothing anyone has said in this thread that he didn't directly address nor anything that weakens his argument. Anyone on the lab leak train right now is basing it purely on bias.
There was a lab leak of SARS1 in 2004 which infected a lab worker and the people he came in contact with. https://www.google.com/amp/s/www.the-scientist.com/news-anal...
https://reporter.nih.gov/search/xQW6UJmWfUuOV01ntGvLwQ/proje...
It's right at the bottom of the summary.
"3. Test predictions of CoV inter-species transmission. Predictive models of host range (i.e. emergence potential) will be tested experimentally using reverse genetics, pseudovirus and receptor binding assays, and virus infection experiments across a range of cell cultures from different species and humanized mice."
But sure, it's fringe and unlikely that the virus leaked out of a lab where it was specifically stated by the scientists applying for the grant that the funding would be used for testing interspecies transmission of bat coronaviruses with humanized mice. The lab doing this being in Wuhan, where the pandemic originated is also totally fringe and unlikely, is totally unrelated, right?