The problem is, even if Planet X really did exist, it has nothing to do with Planet 9. So, in the words of a great American wiseman, "Settle down, Beavis."
Caltech researchers Konstantin Batygin and Mike Brown discovered Planet 9's potential existence through mathematical modeling and computer simulations, but they haven't seen it directly. No one has. If it exists, it's way out there beyond Neptune. But that "if it exists" is important, because it's purely hypothetical at this point. Of course, that's the perfect time for attention-starved sensationalists to get nuts and declare, "It will kill all of us! Sell everything you own and initiate The Purge!"
Imagine looking through a telescope to the top of a mountain miles away -- a place no one had ever seen -- and spotting a vague, dark splotch. It moves just enough to give you a pretty good idea that it is 1) alive and 2) a primate. Then imagine the person next to you starts shrieking, "It's a man! He's got grenades! He's coming to kill all of us! Just like he did the dinosaurs!" That's essentially what this is.