RE: The Mystery of the Missing Antimatter - an Introduction to CPT Symmetry. (Particle Physics Series – Episode 4C)
Well the best is to read the article before commenting ;-),
I am with you fully for 2/, but not so with 1/. In order to respect the CPT theorem, a particle and its antiparticle should have the same mass, therefore respond the same way to gravitational fields, like those of a black hole... As for Hawking radiation, there is no reason to believe that the process of having one of the virtual particles gobbled up, thus the other becoming real, would be asymmetrical: it can either be the particle or the antiparticle, in equal amount.
For the second point, this is what makes most sense to me compared to a much larger assymetry than observed via CP violations and that has not be found yet (if you read the last paragraph, you'll see this). Principle of Occame's razor.
The issue is that no signal from antimatter stars or galaxies will ever be able to reach us because beyond the horizon of the observable universe....
So... because we can't test this hypothesis.. how scientific is it to even propose it?
The debate is open :-)