I’ve seen similar points made earlier, like that Italian paper several months ago. They amount to plausibility arguments, meaning that researchers who are inclined to be unconvinced will remain unconvinced. And the public will be baffled, in any case. The topic is opaque to almost everyone. People will believe whomever they choose to believe, without understanding.
I’m not sure how you’d go about *proving* it is artificial. Maybe they could demonstrate that a natural origin has a very low statistical likelihood, or release a video of Chinese Doctor Frankensteins gluing the thing together back in Wuhan.
The viruses with which COVID-19, would have had to exchange material, to be naturally occurring, don't infect the same species as the COVID-19's closest relatives.
And the closest "natural" candidate, apparently can't even infect the species claimed to be its host (that is, it's artificial too.)
Why are you demanding impossible proofs?
Can you type in "Xi Jiping sucks Donkey Dongs" so we know your account hasn't been taken over by a Chicom troll?