Anyway, it's not obvious to me that the edge of a black hole is the event horizon. The event horizon is mostly empty space too. Maybe it's the ergosphere, which can be further out. Since a black hole is just a region of space, the boundary is sort of arbitrary.
"Nobody has observed a magnetic monopole" is still true, even if systems that behave like quasi-monopoles have been built.
My conclusion (that we can't know for sure that black holes produce Hawking radiation) only makes sense if I was talking about observing actual Hawking radiation rather than analogs, which I was.