The article quotes "Black hole expert Harald Pfeiffer, from the University of Toronto's Canadian Institute for Theoretical Astrophysics" as saying: "Not only we are safe, but probably all the aliens in that other galaxy are also quite safe." Because space is really really big, and the speeding supermassive black hole isn't likely to hit anything.

But clearly that doesn't help anyone living near the path of the black hole in the pile-up of stars resulting from its original two galaxies which merged. And I don't know what effect there might be from the pulse of gravitational wave energy in the opposite direction. Mind you, it's possible that the effects of merging the two galaxies would have been disastrous for a large fraction of the people living there, so the black hole and the gravitational wave pulse would have been just icing on the cake, as it were. ("Disaster" = "bad" + "star", incidentally.) Apart from perturbation of orbits of bodies, the collision of the gas clouds could have warmed things up considerably.