It’s the 21st century. There were many direct flights between Wuhan and the United States every day, as well as with other countries. If the virus were circulating in august that would have given it months to spread to the USA. We know from antibody studies and the lack of deaths that didn’t happen - the virus didn’t spread widely until 2020.
Vietnam has a population of 100 million and a land border with China. They activated their pandemic response in January and have had ZERO coronavirus deaths. Taiwan, again, activated their response on December 31, 2019, and has had only 7 deaths from COVID-19. These numbers are impossible to square with the idea that COVID-19 was in wide circulation in the Chinese population in August or September.
Therefore the idea that it was circulating in human-to-human transmission in China as early as 4 months before 2020 just can’t make sense.
This seems like science in service of politics or publicity - it’s already being breathlessly used as proof that China somehow covered up the virus for months as an attack on western civilization (again, this doesn’t make sense - when Wuhan actually did come under heavy threat from the virus, social media posts and videos did leak out to us in January).