For consideration, consider two smallish black holes, under 
say, 600 solar masses, in relatively close binary orbit with 
each rotating event horizon somewhat extended from the main 
masses.

As the black holes orbit one another, the event horizons 
closely follow the source mass.

Spacetime warpage models two large rotating dimples.

In this example, orbit speeds are less than c.

If orbit velocities of the "hard holes" exceed c, trailing 
event horizon geometry is up for grabs and might even look 
like anything from an  old wobbly rubber inner tube to a 
steel belted black beastie, but back to less than c 
velocity.

Anyhow, as the black holes orbit one another they attract 
gravitationally, the local radiation.

As the radiation is drawn in, and pass thru either of the 
event horizons of the black holes, it is mostly drawn to the 
hard mass below and continue in close orbit around the main 
hard mass if it isn't converted back to particle state 
itself by reabsorption thru high gravitational attraction.

Binary black holes are sort of proximate to one another to 
greater or lesser distances, so the event horizons of each, 
generate two bulges in the spacetime fabric, which act as 
"radiation wipers".

That is, they rotate around and hit any other present 
radiation between the bulges.

Other external radiation then immediately fills in any 
radiation "holes" or "gaps" at c velocity.

Any additional radiation, besides that which was/is 
originally gravitationally attracted, is "caught" or "wiped 
in" by one of the "bulges" which then enters the event 
horizons and a portion of which might find its way to the 
zero gravity port if it exists.

But to have a zero gravity port, both masses have to be 
roughly the same size before any polar emission of radiation 
out the port would exist.

Dissimilar sized masses would warp the rotating zero gravity 
plane between them into a "wok" shaped disk and therefore, 
little radiation would escape under that geometry.

This "eternal" addition to the mass of the binary black hole 
system by radiation accretion and "wiping" might be greater 
than any subsequent hairy evaporation that might occur.

In fact, the black hole would continue to accret a large 
amount of internally closely orbiting radiation over time if 
the radiation did not become part of the main mass.

If for some reason the escape velocity of the black hole 
system dropped to beneath c, the radiation would all be 
released at once, creating some sort of minor novatic "light 
show", perhaps visible from earth.

"High mass" galactic jets dropping the mass to a beneath c 
escape velocity condition would probably only occur if the 
black hole binary masses were in the final stages of orbit 
decay and masses of each were very close and in addition, 
had identical masses or somewhat close to it.

With local hypermassive gravitational objects in the area 
(the Norma cluster) of 50,000,000,000,000,000 solar masses 
(50 quadrillion) at best current estimate, the possible 
variations in geometry occuring may be more than a few of 
radiation pumps and other assorted broadcasting events.

Our tiny little example was just a tad over the minimum mass 
necessary to establish a black radiation retaining hole with 
a small amount of radiation beeping out of the center zero 
gravity port.  

What masses in excess of 5 x 10^16th power can do is up for 
anybody else's shuddering guess.