It works just the opposite...
If they are in the plane of our ecliptic, any Doppler effect caused by planetary revolutions are exaggerated. Also, they can see the transit of Earth across Sol. So the worlds that know we are here are clustered around OUR ecliptic, at least, as far as the search techniques TB was referring to are concerned.
If they are trying to signal us, using this logic, they will be clustered along our ecliptic. Of course, their ecliptics will be distributed randomly to us, and those search methods would not be particularly useful for locating them.