The size of the black hole described in the paper is ~ 20 km, so it is tiny. Even we have millions of such objects (and most likely we do), the chance of hitting something, given the enormous size of the galaxy is negligible.
The black hole in the paper is also ~7 solar masses. If that passed between the Earth and the Moon it would rip apart the earth from just the tidal forces.
Well, if present anywhere in the solar system it would also completely fuck our orbits all to hell too eh?
the chance of that is negligible.
Would we notice if it was to point in our direction?