I still think that Moon is the Mimic. If it was a zombie I doubt it would still be able to operate such an inconvenient suit, and I'm not even mentioning the obvious mechanical noises it makes as it moves, further proving that it's not a human being inside it. But it's also possible it may not be M2 but another robotic creation, maybe even some kind of a prototype mimic(?), and the fact it has Edwin's VA's voice doesnt really mean anything special because he used his and his wife's own voices for most (or all) of his creations.