My guess (and that is all it is) is that these -ista words came into Gringo American usage by analogy with "Sandinista" (a supporter of the leftist Nicaraguan Sandinista National Liberation Front), a word that became common in the 1980s. So I would go with wordinista.
hm. since the suffix is only -ista, -n- is presumably only there to resemble fashionista, and both wordage and wordiness are real english words, i.. don't know. popular use says 'wordanista,' 'wordinista,' then 'wordonista.' i wonder if it was shown in writing when stephen colbert used it.