And this is the amazing leap so many people seem to make: If it is technically possible, then it must be true.
That's what baffles me here: "We cannot conclusively say it's wrong" so it must be right. When did that become a popular mode of reasoning? I can only assume people are so desperate to believe they will swallow this rather than accept reality.
That's not what I'm saying - Where did I say it must be true? I'm saying "We cannot conclusively say it's wrong, thus it's not in the same category as the moon landing".
In reality nobody knows the origin for certain, but IMO you seem to fall for the fallacy you are describing but with the opposite premise - i.e. "We cannot conclusively say that the lab leak theory is right or wrong, thus it cannot possibly be a lab leak".