Yeah, I think this hits closer to home: the zoonotic origins story makes the Chinese government look incompetent. They actually are much less competent than Western popular culture likes to paint them, but emphasizing that doesn't provide a very effective external threat to rally the masses against.

A lab leak plays into the stereotypical German or Russian mad scientist trope of the 20th century: the incredibly powerful supervillain who in their hubris (nearly) destroys the world.