A subsequent BU press release denies that the research involved gain of function, with bizarre arguments including the fact that since it's never been tested in humans (good?) we can't know it's actually more lethal in humans. This is obviously wrong, as many people have pointed out. For example, here's Marc Lipsitch at Harvard:
https://twitter.com/mlipsitch/status/1582574061062098946?cxt...
My original quote is from David Relman, a professor of microbiology at Stanford who I wouldn't expect to "think like a computer scientist". Laboratories have been enhancing potential human pandemic pathogens for literally decades now, as measured by reproduction rates in vitro, mortality in their lab animals, and other similar metrics, and publishing in the open literature. For example, here's Relman asking Baric a question back in 2014:
https://www.youtube.com/watch?v=Aw-nR6-4kQQ&t=2466s
If you were really unware that labs are successfully enhancing potential human pandemic pathogens, then a Google Scholar search for Baric will find many examples.
Anyways, even if you believe (quite falsely) that laboratory gain-of-function on such pathogens is impossible, that doesn't exclude a research-related origin for SARS-CoV-2. That could be a naturally-evolved virus, but one that was sitting harmlessly in a remote cave until the WIV sampled and accidentally released it. The WIV sampled remote areas that no other humans routinely entered, so it's possible in that scenario that the lineage would have died out in bats (or other zoonotic hosts) if the WIV hadn't released it into humans.
Nobody is asserting that genomic evidence shows SARS-CoV-2 to be natural anymore. Even the strongest proponents of zoonotic origin have moved on, to more complicated epidemiological and phylogenetic arguments like Pekar's paper.
In order to make a pandemic Virus the components must be finely tuned to each other. That is only possible through massively parallel evolution. A lab can't do that. When a lab combines Viruses, it's mostly to learn the individual contributions of the proteins. These Viruses are way less "fit" overall.