I think the point is, it may be an engineered object, and therefore of alien origin.. And whilst it will miss the earth, by the time it arrives we won't be able to directly see it, so could be the launch platform for an alien invasion..
But it's Avi Loeb, a nice enough person, but he always jumps to 'Its aliens' and whilst he does tend to follow the science, he could do with reigning things in a bit..