Thank you for posting.
Very interesting article.
But it does not discuss dark matter.
From what we can tell, dark matter is a halo that galaxies collect, and does not concentrate in the disk at all.
This article concerns very energetic and hot particles.
Near a galactic center would indeed be a highly radioactive place, with or without benefit of the black hole feeding.
But this has to be looked at in perspective.
This view is seen from a great distance.
Up close the gasses and high energy particle would be very diffuse.
So diffuse that stars have a heliopause where their local particles plow into the intersteller winds.
We observe the region of orbit above earth where the ISS resides to be a vacuum.
In actuality it is filled with the output of the sun that creates the heliosphere.
Where that heliosphere pressure is stopped by the intersteller winds forms the heliopause.
From a great distance and with sensitive instruments the earth would be observed to reside in a great solar wind blasting out a big heliopause bubble in the intersteller wind cycling into the galactic center.
Even when a black hole is gobbling up stars, the only area with any density is at the event horizon.
What we have to keep in perspective is on the local level, it is so diffuse that it is perceived to be a vaccuum of empty space.
Whatever works, use it.
A good idea stands on its own value independent of authorship.
If it stands or falls on the credibility of the author, maybe it isn't such a good idea.