Gladius, I usually agree with you, but you are way off base here.
The devil indeed has supernatural powers. He can use people to talk through as if they were nothing but marionettes. Ever read any rock music lyrics? They are full of fantastical visionary wisdom, like that of a Greek oracle. Satan possesses all these people. He plays around with the truth, through the mouths of others, and often sounds like a prophet.
What makes you think he couldn't possess some kids to see the Virgin Mary? I don't think that's what happened. But it is SO VERY possible.
The reason CM is saying that is because the apparition was approved by Benedict XV, who he considers an anti-Pope because of the BoD-confirming 1917 Code of Canon Law. What he is saying is entirely in character, and consistent, if you accept his logic.