An Artificial Construction

[JoJo_Jost]

Just to avoid a misunderstanding....
While I clearly expressed that I have some doubt that the apparent spaces in the MS delimit units that are equivalent with words in a plain text, I am also not aware of any evidence that they are not. 
This is just a hypothesis.
Or, rather than a hypothesis, I want to point out that this is an assumption that appears completely reasonable, but is not a given.

The fact that certain character shapes preferably appear adjacent to these apparent spaces could be seen as evidence for either option. (I don't think it is valid evidence either way).

I definitely agree with you, but that’s not the point—we’re still comparing apples to oranges here.

If a text has only 7–8 rules to define 90 percent of the spaces (the rest are likely artifacts), then you CANNOT compare this highly rule-based system to a normal language, in which there are significantly more rules (well over 50 for MHD and Latin, depending on the text type). That in itself makes no sense. It doesn’t matter whether they are actually word boundaries or not.

I think that’s the problem: it logically weakens the validity of any statistics based on word boundaries in the VMS.

Or am I wrong?