I am really reluctant to weigh in here, because Gene knows a million times more about physics than I will even know. But it seems to me that he has made a mistake in saying: ... These dynamics are time reversible. While it is true that the time
reversal of a black hole satisfies the equations of general relativity, such an object would gravitationally repel ...
I do not see this. Imagine an object falling toward an ordinary, forward-sense black hole. It accelerates as it drops into the potential well. Before the object gets too close to the event horizon, stop running your movie camera and replay the film backward. In the time-reversed view, we see the object rising away from the black hole, and decelerating. Surely, if the reversed black hole were gravitationally repelling, the object would accelerate away. My intuition is that the force field around the reversed black hole is identical to the one around the forward-sense hole.