The things is the Wuhan lab usually publishes on new viruses they discover and this one hadn't appeared in the literature previously. Which isn't to say that a Wuhan researcher couldn't have carried it back home from a bat cave in their lungs.
The popular hypothesis includes Gain of Function research in the lab to make it so contagious (which, per your claim, would mean that they would have published about it?). If it came from the cave directly into the lungs of patient zero, I'd think it'd effectively be considered zoonotic.
Have you poured over the literature? Where are you getting this information? Do you think China is open and transparent and wouldn't cook their books?
Being a regular listener to This Week in Virology where they've had a number of guests on who discussed this. The thing is the Wuhan Institute of Virology was a normal lab collaborating with researchers around the world. I'm sure it's possible that the local books could be cooked by the government but that doesn't change the fact that the collaborators also have the books. If they'd known that this particular virus would escape then obviously they wouldn't have shared info about it. But how would they know that unless they planned to release it? And planning to release it doesn't make sense for all the normal reasons.