The "spreading indoors" argument that Bret Weinstein made was mind-numbingly stupid. I know he has a degree in biology, but this is just embarrassing.
He's making an argument that this virus has been selected in a lab for a specific transmission mechanism. That means that the virus would have to have undergone many generations of animal-to-animal transmission in a lab. There's no reason why a virus would adapt to transmit well if it were being studied in cell culture - because there's no transmission involved.
So Weinstein's theory requires a large-scale operation in which scientists keep large numbers of animals in the lab, and allow them to periodically come into contact in order to possibly infect one another. This has to go on for many generations, with the researchers constantly bringing in new animals to be exposed, until the virus "forgets" how to transmit outdoors. Where does Weinstein suppose this massive research operation occurred? The people he's alleging did this research are well known (and highly respected) scientists who publish their research in top international journals like Nature. Why did they keep silent about this massive research program, and how is it that none of their international colleagues had any idea about it?
Meanwhile, there's an obvious reason why the virus might transmit better indoors than outdoors: many respiratory viruses do. That's one of the explanations for the existence of "flu season" - people spend more time indoors during the winter. Indoors, people are closer to one another and there isn't as much air circulation.
You don't have to invent completely unsupported theories about scientists carrying out large-scale, secret animal infection experiments in order to explain why a respiratory virus might transmit better indoors than outdoors. But Bret Weinstein is doing that, because he likes attention. I was on his side in the whole Evergreen saga, but now that he's become a celebrity, it's gotten to his head and he's saying stupid things to get attention.