But we are not talking about the galaxy, we are talking about the solar system. 27 mega-miles is a pretty substantial buffer for something attracted to the sun. I don't recall if the author mentioned if the object was even on our plane.
May be not but he did say
While 2013 YP139 is classified as potentially hazardous and its orbit may bring it within 300,000 miles (490,000 km) of Earth, it wont do so for at least another century.
That is right about the orbit of the moon.