The Voynich Manuscript is a cipher because...?

[Anton]

Of your three points in favour of a cipher, I agree that point 2) is good. But point 1) is ambiguous, and point 3) is incredibly thin.

Point 3) is not that thin when we begin to consider possibilities of what this label may stand for. Every possibility yields quite strange outcome. Like, if it stands for a number, then from the viewpoint of an unknown language we should admit not only unknown script, but also an unknown numbering system. If it is a noun, then we have a one-letter noun (is that at all possible in a non-hyeroglyphic script?) And so on.