Official names aren't exactly "official". Even if they are official, we should take practicality into account. Officially, Arcanine is a "Legendary Pokemon". But, everyone knows that offical classification has nothing to do with the practical usage of the term "Legendary". I really hated the naming of Deoxys with "Fr, Lg, and E" forms. Everyone used the practical descriptions of "Attack Deoxys", "Speed Deoxys", and "Defense Deoxys". To have the site use a different name was really silly, considering that this site is focused on the Pokemon metagame, which is, by definition, outside the game and "unofficial".
Everyone knows how Wormadam will be referred in practical terms. It will be a reference to the non-Bug type -- Grass, Ground, and Steel. Do you honestly think anyone will ever refer the Steel Wormadam as "Wormadam-Trash"? Hell no. Same thing for the other cloak names, all of which are very cute and clever names, but will never make their way into common usage.
We all know that Wormadam, if it is ever discussed at all, will be discussed in terms of its non-Bug type. That WILL be the "name" used on Smogon -- on posts, messages, etc. You know it, I know it, everbody knows it. Now, the only thing to decide is if the site wants to list a name that is related to it's common name, or it's "official" name.
IMO, the common name is the only option that should be considered. But, it appears that I am in the minority.