Earlier quoted context omitted.
The “zero evidence” claim is fun because every day there is a failure to discover an origin species is de facto evidence of a non-zootonic origin, since that evidence is not subject to being hidden and is highly incentivized to find given it would be exculpatory.
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.
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.