There may be more wildlife trade to the south, but Wuhan has a substantial amount of wildlife trade, along with being the trading and transport hub in a region

There may be more wildlife trade to the south, but Wuhan has a substantial amount of wildlife trade, along with being the trading and transport hub in a region with lots of Rhinolophid bat habitat in rural areas (and areas where the human population has a considerable (several %) background prevelance of bat virus antibodies. Appearance in autumn could easily fit with infection from a traded animal a couple months earlier and perhaps a couple of host jumps to gain mutations that conferred pandemic potential. We won't know just how much of a long shot - or just how parsimonious a Wuhan emergence was unless we actually identified early hosts and the likely chain of events that occurred, but depending on the details, even despite the points you raise Wuhan could end up the 'likeliest' spot. My point here is assuming zoonotic origin, it isn't a one in a trillion coincidence that Wuhan has a coronavirus lab. It has a coronavirus lab for the same reasons a zoonotic origin appears likely - it is within trading/sampling expedition distance to bat caves and is an urban hub. Perhaps Guangdong still was the more likely candidate for a pandemic emergence, but based on what we know today Wuhan appears to be 1-in-100 betting favourite, plus or minus an order of magnitude.