The "zero evidence" claim is a blatant attempt to shift the burden of proof. In my opinion the burden of proof remains with those hypothesizing zoonotic origin.
>>t0rt01+(OP)
I’d suggest the opposite. [edit: not the opposite, the same!]
If it’s conceivable that gain of function research can release a virus that kills millions, then the burden of proof is with the researchers to prove that they’re safe and this didn’t happen.