The Book Switch Theory

[ReneZ]

Indeed there is no direct evidence for those claims.

I'm sorry, but there is none, direct, indirect, or inferred.

"could have" is entirely subjective. 

How can it be that we should:
- seriously doubt that Voynich found the Marci letter inside the Voynich MS (which is a trivial thing), just because there is no photograph of it happening
- seriously consider that he faked the signature of a completely unknown guy into the book (which is a very complicated thing), even though we also have no photograph of him doing it

Talking about motive, he obviously had much more of a motive to link his MS to Bacon, than to the court of Rudolf.

Because of that, he should have put a fake Dee signature.