According to the paper, they did it in order to figure out why SARS-CoV was able to infect humans, while numerous other SARS-like viruses are not. Their hyposthesis was that the critical feature is a particular sequence in the protein found on the "spike" that the virus uses to bind to host receptors. By constructing a new SARS-like virus with the desired spike protein, they were able to validate that hypothesis.

It seems to me that if there was any malign intent behind this work, they would not have published a paper on it. Obviously, that's doesn't preclude the possibility of an accidental release from the same lab twelve years later. As far as I know, there's no way to prove whether 2019's coronavirus was engineered in any way.

I want to repeat what I've said in other comments, because what I initially said was inaccurate. These researchers didn't actually create a new coronavirus, but rather a much simpler and safer virus purpose-built to test some receptor-binding structures. This is a well-established way to study viruses safely.

This kind of work is critical if we're to learn how to develop vaccines faster in response to epidemics.

From

> "The evidence we have is that the mutations [in the virus] are completely consistent with natural evolution".[19] Bedford further explained, "The most likely scenario, based on genetic analysis, was that the virus was transmitted by a bat to another mammal between 20–70 years ago. This intermediary animal—not yet identified—passed it on to its first human host in the city of Wuhan in late November or early December 2019" [1]

"20-70 years ago"! [2] Also important: "was transmitted by a bat to another mammal". That could imply it wasn't from bat soup or bats directly.

[1] https://en.wikipedia.org/wiki/Misinformation_related_to_the_...

[2] https://archive.is/X3VGB