Voynich is encrypted ENOCH

[Jorge_Stolfi]

By accident he gets caught red-handed. 
He would easily get away with it, claiming that the spirit of Moses was speaking though him

That is in fact a basic tenet of Espiritismo ("Spiritism") or Kardecismo, a major Brazilian religion.  It states that the spirits of the deceased can be summoned by "medium" at seances, can be "channeled" by particularly capable mediums to You are not allowed to view links. Register or Login to view.. 

and there is nothing in the text that Moses wouldn't say

But the Book of Enoch is not like that.  It tells tons of things about the Heavens that not even Moses would know, and kinda contradicts Genesis in some points.   I can imagine that many Jews would have been reluctant to accept it as Scripture, even a few centuries BCE.

All the best, --stolfi