Interesting hypothesis. How could we test this?
Here's one possibility: From your illustration, wouldn't we expect an outward acceleration along the equator increasing from zero at the middle and maximum eastward at the east edge, and maximum westward at the west edge? The magnitude of the sideways acceleration would depend on how fast the earth is spinning as well as how far you are from the axis of spin. Are such accelerations observed? If not, is this a plausible model?