If we leave out the...questionable evidence of trips around the southern hemisphere, there's still evidence that the flat Earth is based around the south pole. Antarctica contains fossils from a time when it was warmer, which suggests that at one point it was closer to the equator. this would work fine in a south pole based FE model, as Antarctica is free to move around with continental drift, moving from warmer to colder places, and fitting in nicely in Pangaea. With a north based model, Antarctica is this vast ring of mountains, apparently completely immobile in continental drift and incapable of becoming warm enough to support the fossils it holds. It also leaves a huge hole in Pangaea where Antarctica would be.
There's also the fact that there's a lot more sea in the southern hemisphere than the northern hemisphere. With the North pole model, you end up with Australia, south Africa and South America either stretched out of proportion or separated by insane amounts of sea. A south pole based model would give a lot smoother land coverage.
Finally, there's a lot more researchers at the South pole than the north pole, along with a larger number of tourists and other civilians. The idea of the North pole based model might have been planted by this vast, world spanning conspiracy, so that when people go to the south pole to look for themselves, they found no edge and thus assume the world is round. They are free to circumnavigate the south pole as many times as they like, with the people running the conspiracy safe in the knowledge that nobody will check that the North pole is the same, due to the fact that the north pole is far more difficult to circumnavigate via sea.
Of course, I still believe that the Earth is a globe. Not that it affects me in any way, but everything seems more logical that way.