From the start, the problem with these lab arguments was that they were made by people who had zero evidence. Making up a plausible story and speculations are not evidence.

The bottom line is we will never know, since China is not exactly a free country were potential eye witnesses can be interviewed freely. The market theory was always more likely and more dooming for China, though. It's easy to beef up the control of bio labs, it's way harder to close down all animal wet markets. Officially, China claims they have done the latter but I've heard that they continue to exist all over China.