It's not likely that life will survive long enough to form civilizations that close to a black hole. It has probably fed like this many times before already.
How close to a black hole? This isn't a common-or-garden black hole, it's supermassive. If it's (300M years ago) suddenly started producing intense radiation that we can measure here, then I assume that anyone in the galaxy that can see the central region is receiving a lot of radiation, as well as a storm of high-energy particles.