Although reasonable, one theory ("the bat coronavirus was transported by scientists to the lab that studies bat coronaviruses") involves no illigal activity. On the other hand the counter-theory ("there was illegal bat trafficking from a small mine in Yunnan") involves speculation that something happened that we don't know about. Strictly speaking, the lab leak theory has more observed evidence. Presumably the Chinese government would have identified and explained if they found bat traffickers.

We know the lab was aware of RaTG13 - they produced a sequence quickly that no-one else had seen. I know nothing about the situation but it would be interesting to know where exactly the sample was being sequenced. I doubt they did it in the mine, samples must have been transported to some lab.

I used to think 99% chance zoonotic, but the fact the similar virus was known to the lab was enough to drag me to thinking it is probably a toss up. Lab leaks do happen, this lab was studying bat coronaviruses. It is possible.

> On the other hand the counter-theory ("there was illegal bat trafficking from a small mine in Yunnan")

One theory is that people mine bat guano from caves, so there's no need for them to ever touch a dead bat.

>he similar virus was known to the lab was enough to drag me to thinking it is probably a toss up.

A human generated virus wouldn't be similar in this way to a wild one. You would take a candidate virus and splice in genetic material from a different one. The new virus would match 100% in most places and then be completely different in a few places.

This is not how they conduct gain of function research. It's uses serial passage (using biological hosts and the virus's own variations). This produces vary little evidence of manipulation.