Re: manufacturing viruses generally: this is just scarless DNA editing and it’s been around for over a decade. It’s not unique to this situation at all, it’s the modern bread-and-butter of molecular biology and related fields. It has been possible to produce lab strains without obvious signs of engineering for a long time. This isn’t really a counterpoint to the idea of engineering a virus, just want to point out that it’s not special or damning that they also started using these very standard techniques in their own work.

Re: the genome looking like it came from East Asia, this is because it has homologs from bat coronaviruses in caves in and near China. A lab-engineering theory would require that it specifically be made to look like it came from certain areas of China or that after realizing it had gotten out of hand, they used internally documented origins of the genome, which would’ve had to come from a library of bat viruses from those areas, to create a scapegoat.

It’s possible, but it’s multiplying the coincidences you’d need to have and that always damages theories. Though to be clear, I don’t put the malice outside the capacity of the US MIC. I am more dubious about their competence, though.