I already have.
Please quote where you have (and more importantly than anything else, the source that supports your claim that all black holes make gamma rays).
we can reasonably infer that their gravitational fields are composed of electrons.
Gravitational fields are not made of electrons.
if anything like a QGP forms the outer layer of a black hole (i.e. something that's positively charged)
It doesn't. Black holes don't have an "outer layer". The event horizon is not a physical object.