The Voynich Manuscript is a cipher because...?

[Anton]

Many scripts at this time used characters to represent numbers

Yes, I am well aware of that. Old Russian did exactly that.

Being both an unknown script and an unknown numeral system would be pretty much normal

What is not normal is that this supposed number is represented by a symbol which is extremely rare in the corpus.

Many languages have nouns which have a single sound.

Here we have a single letter. Is that OK?

Most importantly, it's not hugely convincing that this single stroke is a label.

What's it, otherwise?