I'm pretty sure that the 40cm wouldn't change though, would it? Because if it did, then the electron would have contracted space due to velocity... And the tube wasn't in motion. I hope anyway.
Tower B's mass has a velocity of geostationary satellites due to the Earths rotation, and Tower A only has velocity from the Earth's rotation around the Sun, which is negligible, therefore Tower B would remain in a geostationary orbit while tower A would return to Earth.