Think of it like old astronomers who still refer to Pluto as a planet. They know it's not officially a planet anymore, but they still call it one because that's what they like calling it and they don't give a shit.
And let's be honest...."official" in that case just means, "what other people think."
I think it's just change of habits. For example, in russian "coffee" was masculine gender for long time, until significant amount of people started to erroneously call it in neutral gender. Now rules is "okay" with both.
I like to play with those sort of people by saying that the planets of the solar system are: "Mercury, Venus, Mondas, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, Rupert".
While one of those entries is strictly fictional, if Pluto belongs on the list there's no reason to exclude Ceres or Eris (though in the true spirit of Discordianism, I have to stick with the initial, fictional name for the final known planet).
That's what I can't figure out. It is what it is. What a few men decide to call it, doesn't change what it is. It's mass, radius and composition are not in debate. Those are the things that matter (no pun intended).
And let's be honest...."official" in that case just means, "what other people think."