Speeding supermassive black hole

The CBC just reported the discovery of a supermassive black hole, of the kind that usually sits at the center of a galaxy, travelling at extremely high speed away from its galaxy.  It's believed to be the result of the merger of two galaxies, with their respective central black holes merging and being flung away.

My intuition explains this as being somewhat like the old children's game "Battling Tops".  In that game, players launch small spinning tops towards each other in a bowl-shaped "arena".  The tops are spinning in the same direction, so at the point of contact, the rims are moving in opposite directions.  The collision transfers some of the rotational momentum of the spins to the tops with respect to each other, slowing the spins and kicking the tops away from each other.  Eventually, the tops slide down the bowl again, and after a few collisions, at least one gets knocked over; the winning player is the one whose top is standing last.

With the black holes, getting flung away from each other after "contact" doesn't work so well.  So a massive pulse of gravitational wave energy gets flung in one direction, and the merged black hole heads in the opposite direction.

Or so my intuition says.  Dammit, I'm a doctor of chemistry, not a doctor of astrophysics.