This is definitely the most sensible explanation, since it's quite well known that Wuhan is the most important transportation hub in China since even before the lab was a distant dream in some postdoc's imagination.

And China does have the world's largest annual human migration, in the Spring Festival.

If I was in the planning department at whichever ministry that made the final decision on placement, putting the most prestigious and well funded lab studying dangerous human transmissible viruses at the world's most likely place to originate such a virus is an obvious choice.

i.e. during a few weeks every year Wuhan could easily be 10x more likely to be ground zero then any other city ever.

> The lab is there because there are lots of virus sources there.

That's patently false.