Well, on a hill, and indeed anywhere on Earth's surface, the soil is compressed (and falls down, like everything else) because it's "shielded" by the rest of the Earth. The FE point is that the soil/rock touching space does not obey the same laws, because it is not shielded (since all of the mass is in front of it). I know, it's actually really dumb and hard to believe. In fact, it's as if there's a giant metal plate on the back of the Earth, and something's pushing it, but you have to remember that UA has to affect all particles in space, so the rock in the Earth itself is shielded by the layers "behind" it.
Indeed, the mathematics of how much things get "shielded" are impossible to work out because FE hasn't given anything close to that. Unfortunate. For their hypothesis to work, the shielding is only accomplished by matter "behind" the other matter, where the "behind" is with reference to the direction of universal acceleration.
The problem with this whole idea is the oblong planets, the replacement of one somewhat understandable force with many invisible, completely unquantified forces, and ad-hoc hypotheses that have not been observed/confirmed elsewhere, unlike gravity, which has been observed at laboratory scale.