The pessure of the air inside the body can simply be adjusted to match the surrounding water pressure. All it takes is the same mechanisms that a scuba diver uses.
Trying again to explain. It's like wieghtlessness in a pool. The water surrounding the pilot acts in almost the same way as the water inside the pilots body, thus, the g forces and pressures are almost the same. While he might feel something, the principles of boyancy apply. This isn't rocket science (well, maybe it is, in this case).
S