>>seymor+(OP)
Presumably they specialised in coronaviruses because of the proximity to a bat population with coronaviruses, making sample gathering much easier? Are there other areas with significant coronavirus hosts? Are there other labs that specialise in coronaviruses to the same extent? The two seem linked to me, although I have no background in this area.
So we'd a priori expect coronavirus to originate in the area with coronavirus hosts, whether it was through the lab or the market...