I believe it is entirely possible that the apparition is legitimate. If I recall correctly, it was after the apparition that large numbers of natives abandoned paganism and human sacrifice for Christianity. While I don't think that RCism is the true Church, I really doubt that it was likely that random natives in rural Mexico were going to find out about Orthodoxy in the 1530s so I'm willing to believe that the Virgin Mary took an "executive" decision to appear to them to convince them to stop human sacrifice and paganism even though they didn't end up Orthodox (step in the right direction, etc.).
Just my personal opinion, and not official Orthodox teaching. I have seen the icon of Our Lady of Guadalupe in one OCA bishop's home though, for what it's worth.