Dear Christian,
Darryl Jay Leiter would be truly content to see the essay you wrote together.
This is a fine way to continue the cooperation even when a part of the group is no longer in our causal universe.
I read the essay, but you lost me with the equations, however the most important thought is clear to me, the essence of BH's is not yet clear to us and you together also doubt the "existence" of singulairities.
In "THE CONSCIOUSNESS CONNECTION" my perception is that singulairities cannot exist in our causal universe, because it is limited by the Planck length and time.
What you are posing about the event horizon is indeed a foundational question, this event horizon is an exact limit and when you don't accept singulairities there are also no exact borders , because the Planck length is the minimum length, after that there is no longer cause and effect.
I hope you will read/rate and comment my essay.
Wilhelmus