Imitatio Homeris

My extremely erudite friend at Laudatortemporisacti recently posted on a title, "Imitatio Homeris," which should be Imitatio Homeri. I think the gaffe occured because the author thought, for whatever reason, that Homer (Homerus in Latin) is a third declension rather than a second declension noun, by analogy with oper. Thus, we have opus=operis and Homer=Homeris (operis and Homeris being the genitive or possessive forms). I think the author thought that Homer, not Homerus, was the Latin name, which, if I'm not incorrect, resembles a third declension noun.
Of course, this is based on my very fundamental, rudimentary, basic, and bare bones understanding of Latin. I know less Latin than most babies, but I wanna be smwart, so there ya go : )