The Modern Forgery Hypothesis

[Mauro]

foldouts are not documented from that period

Many other things are not documented from that period. The most obvious is the text, if it is a cipher, it is unbreakable, from a period where homophonic ciphers were the most advanced technology.

But if it's a cipher created in the ~1920, it's unbreakability 100 hundred years later is as strange as if it was created in 1420. At most this is evidence against the VMS being a cipher, not evidence in favor of Modern Forger Theory.
And I'm not sure homophonic ciphers were the most advanced technology near 1420, I think they already used nulls, polyphonic susbtitutions and a sprinkle of codewords, but I may be mistaken, dates have never been my strong point 

Then the Alberti disk on f57v. That kind of cipher disk, if indeed that is what is depicts, was not invented at that time.

But, is it an Alberti disk?

The plump bodies of the nymphs, were not at all depicted in that way in early 1400s. Not even close.

Ah I'm not arguing on that, I'm no expert in the depiction of nymphs in early 1400. They just look as badly-drawn female figures to me, and the ideal of beauty for a woman at those times was plumpier than today.

Poxleber as a word is only recorded in literature after 1500.

But 'poxleber' is a marginalia, you need to assume it was written by the original author of the VMS for this to be relevant. 

Some images in the cosmology section have non-trivial parallels in microscopy imagery.

But also to many other things, from rose windows to Citrus fruit slices to diagrams of all sorts in manuscripts, from XVth century included

All of these observations, and more, should be enough to at least look at this with a critical eye.

Which is indeed what I try to do. I'm not particularly attached to one or the other theory about the VMS, it could have been written at any time between ~1420 and ~1920 and it would be an interesting artifact anyway from my point of view. I just think the evidences we have strongly disfavour the XXth century.