That's a neat idea.
You see how the entire conversation was reframed from demoting Pluto?
Babylonians knew about the 'tenth' planet, everyone and their mom knew about it. And there's a lot more in the ancient histories to learn about it.
So 'scientists' decided Pluto was no longer a planet, then the 'tenth' planet now becomes the 'ninth' planet, and we get articles like this.
And if you wanted to continue calling it that, your position on Pluto could still be flexible, because you could say "X" means unknown, not 10.
That's a neat idea.