They use AU because using LD would make the story a lot less sensational.
It’s like 15 LD so it’s not even CLOSE.
Also, the posted article says “within 2 million miles of Earth’s orbit” when really, this December, it’s only coming within 6 million miles of Earth.
There’s a big difference between coming close to Earth’s orbit and coming close to Earth.
For me the takeaway is that if NASA classifies this object as a “potential hazard” it means there aren’t very many hazards out there, at least not that we now know about.
It's not close.
Next time they can get an even more hysterical headline by reporting it's going to pass fewer than 11 light seconds from Earth.
Whew! (Still not close...)