This isn't my theory, i believe in an infinite earth. Nor did I change it, that is what I've said the whole time. I suggest you learn to read.
Furthermore the center of gravity would not be at the North Pole, it would be below it. That is of course assuming many many things we can't really assume. So would there be a slight pull downwards and towards the south pole? Sure, but it would be weak enough horizontally that it wouldn't be detectable. Except perhaps at the South pole. For the deeper the earth is, the less it would be noticable.
Unless you can provide actual numbers for the mass, depth, and size of the flat earth as well as the topography beyond the icewall you have no feet to stand on.