Who has the Voynichese mindset more?

[Koen G]

Maybe they realised that even they could not read their own cipher or that the contents of the manuscript was not of much value i.e. bad medicine or bad science. 

This kind of reflection would be unusual in the medieval context. If you have a reason (some authority) for writing something down, you are not going to disprove it empirically and then regret that you trusted the source. Especially in the field of medicine, they could get away with a lot. For example it would still take several centuries after the Voynich was written for people to realize that bloodletting wasn't a cure for everything.