If the gases illuminated when they passed near the black hole, and
If the black hole is 26,000 light years away, and
If the black hole awoke only 300 years ago, THEN
How could the brighter light from the illuminated gas have reached us by now to figure this out?
What do I know . . .I’m a only a banker.
It can't be quite that simple or the gas cloud would be behind the black hole.
The X-rays from the 'feeding frenzy' are long gone. Humans were too busy killing each other to notice. If we had we might be able to use this pulse as a fine calibration tool on distances at the galactic center. We still can, it will just take many years and additional gas clouds lighting up.
In any case I'm inclined to give the journalist a pass on this one. If the journalist had actually understood he or she would have been unable to convey it to the public without resorting to some lame metaphor (cosmic echo) that would only serve to get the mouth breathers to think they understand.
They should include a diagram. Language is a really blunt instrument.