Another way of thinking about the hollow black hole is to think of a bubble with enormous surface tension. Where does the surface tension come from? Gravity. Each particle is so close to the next particle that they are basically gravitationally bound to one another. The stream of particles moving at near light speed around the event horizon could be thought of as an unbreakable sheet of paper, that as far as the particle is concerned the universe is two dimensional... forwards in time. There's no falling downwards because of the kinetic energy making you go forwards, and the enormous gravity of the particles occupying almost the same location in spacetime, much closer to one another than in atoms where EM dominates. The only effect the downwards gravity of the entire system has it to create the curvature rrequired to maintain the sphere.

Another problem with singularities is that as they approach one another, their velocities will exceed light speed. We have a problem here if the singularities are where the mass is.