What is remarkable is recognizing that WE would have that energy too! We are, after all, moving at incredible speed in the UA model. At such high energies, it would not be possible for atoms to stay unionized. Our bodies would literally disintegrate into elementary particles.
I don't think that people in a spaceship running near light speed should disintegrate, provided the spaceship has a good shielding. But I see another question here:
What about the 'space' around "accelerating earth"?
Is it empty? Is it really empty? Not a single atom, not even a small photon emitted by background radiation?
At that speed "accelerating earth" must have obtained meanwhile, a single atom in the course of earth could have an impact like an atom bomb. The frequency of a photon emitted by background radiation could be shifted to ultra hard X-rays.
Yeah, you are probably right about not disintegrating. But the shielding would not come into play regardless.
I agree with your comments regarding space. It is not a perfect vacuum, and the density is about 1 proton per cubic meter (on average). So indeed, they would impact the Earth at tremendous energies. Or from the proton's perspective, we would impact it with tremendous energies.