I think for an eternal black hole, one coordinate system describes all of space-time as a moving sidewalk moving towards the singularity in a roughly Newtonian way with space moving faster than light beyond the event horizon. Since simultaneity is relative, maybe the region outside the event horizon can be given another coordinate system where the exact time inverse of space getting dragged in is occurring and the time inverse of the event horizon is called the antihorizon. Anything coming out of the black hole from the antihorizon in finite time in the second coordinate system will have always been outside the antihorizon in the first coordinate system.
Since the first coordinate system describes all of space, does that mean the region of space beyond the antihorizon doesn't exist at all so the second coordinate system doesn't describe the space beyond the event horizon which actually exists but does describe the space beyond the antihorizon which doesn't exist?
In other words, space has an edge in the second coordinate system. I think that according to the big bang theory, black holes can exist but white holes can't exist because they can never be created and when a black hole first forms, regions of space closer to its antihorizon in the second coordinate system start existing but after the black hole gets really old, space is so severely warped really close to the antihorizon in the second coordinate system that the region of space beyond it doesn't exist at all.