Black holes destroy information don't they - they would be neither matter nor antimatter. Nor energy, for that matter. They're just point mass. Which implies that both matter and antimatter would be attracted to the black hole equally, but that kind of breaks the idea that antimatter reverse-curves spacetime, doesn't it?
So anti-black-holes would have to exist in a "antimatter has antigravity" universe, wouldn't it?
Which contradicts the idea of black holes destroying all information.
This is called the black hole information paradox. Today most physicists believe that hawking radiation preserves quantum information. Hawking himself made a bet that it doesn’t, but by 2004 he had become convinced and conceded the bet. But as far as I know this is still an open question - we’ve never detected hawking radiation experimentally.
So anti-black-holes would have to exist in a "antimatter has antigravity" universe, wouldn't it?
Which contradicts the idea of black holes destroying all information.