That logic does make sense with the default layout of the left touchpad being used as the scroll wheel, considering that the element that is being scrolled (the screen) is on the right side of the element that is controlling the scrolling (the left touchpad). If someone were to swap the touchpads (so that the left controls the pointer and the right controls scrolling), they would probably also want to invert scroll direction if they want to follow that cogwheel logic.