That is serious and useful, unlike the groundless claim of natural origin. The lab in Wuhan has been publishing coronavirus research for many years. In some of the research, they cause bat viruses to replicate in human cells by using the ACE2 receptor... exactly as this pandemic does.
Here is China making a virus like this one, even acting on the ACE2 receptor and testing it in human cells, publishing it in early 2008:
When an outbreak of exactly that type of virus happens right next to the lab, the only reasonable assumption is that it came from the lab. If there were a sudden outbreak of smallpox next to the CDC lab in Atlanta, we wouldn't just shrug it off as a natural occurrence. The same applies here.
> Here they are again, years later, still playing with extremely hazardous coronaviruses that act on the ACE2 receptor in humans
"Playing with" as in "identifying and sequencing the virus in wild bats". The editorial notes say "The results provide the strongest evidence to date that horseshoe bats are natural reservoirs of SARS-CoV."
The location is... interesting, but it's also near a large wet market with a wild life section in a big city, pretty much exactly the circumstances you'd imagine to see natural transmission.
It kindles the imagination but it's not really a smoking gun.
We won't have a smoking gun unless somebody from the lab tells all, which would involve going to prison in China or claiming asylum in a different country. Such a person might even be ignored unless he provides wikileaks with a hard disk full of lab data.
They were definitely doing more than just "identifying and sequencing the virus in wild bats". They purposely caused bat coronaviruses to become more capable of infecting human cells. It's a cool experiment, but far too dangerous to attempt. One of the modifications was to use the ACE2 receptor. This receptor is found in humans, not bats. The pandemic uses that receptor.
Here is China making a virus like this one, even acting on the ACE2 receptor and testing it in human cells, publishing it in early 2008:
https://jvi.asm.org/content/82/4/1899
Here they are again, years later, still playing with extremely hazardous coronaviruses that act on the ACE2 receptor in humans:
https://www.nature.com/articles/nature12711
When an outbreak of exactly that type of virus happens right next to the lab, the only reasonable assumption is that it came from the lab. If there were a sudden outbreak of smallpox next to the CDC lab in Atlanta, we wouldn't just shrug it off as a natural occurrence. The same applies here.