Oh that one, yes I had heard about it at the time. It did initially look like it may be something other than what it turned out to be. And I agree it is certainly one of our strangest encounters so far. But it hardly fills the Niburu Myth :)
Most Niburu doomsayers are hell bent on describing it as a hidden rogue planet, lurking in the outer reaches of our solar system, or I heard one say we had a mirror image earth on the opposite side of the Sun (Niburu) that we can't see as the sun is always in the way lol
But I guess if we have expanded the definition of Niburu or planet X to include large (non planetary) objects such as Oumuamua..
Well then there may be lots of Niburu's lurking out there.