Speak of the devil :lol:

to what would you assign, in the universe I described, lengths greater than 5 cm and less than 1 cm?

No object in your universe has these lengths, so I would not assign them to anything. This doesn’t at all mean that I would assign them to the state of nonexistence.

It is now clear to me where your confusion lies. As Echarmion points out, you are equivocating Nothing as a state of nonexistence with Nothing as a quantifier. It is like the old joke:

“1. Nothing is better than eternal happiness.
2. A ham sandwich is better than nothing.
3. Therefore, a ham sandwich is better than eternal happiness.”

It is clear that ‘nothing’ in 1 is being used as a quantifier, while ‘nothing’ in 2 is being used to refer to a certain state of nonexistence.

Therefore, your argument does not work because it commits the Fallacy of Equivocation.

if you're like most of us then what you'd be saying in your mind would be: "1 cm - C; 3 cm - B, 5 cm - A, 0.5 cm - nothing, 9 cm - nothing

I would say this in my head, but I would not thereby mean that the state of nonexistence is 0.5 or 9 cm long, since the state of nonexistence cannot have a length. Rather, I would be thinking that "There is no object in the universe which is either 0.5 or 9 cm".

What is wrong in saying "nothing is greater than nothing"? Is it not true that there can be nothing more nothing than nothing? Doesn't this amount to saying nothing is greater than nothing? Apply the same principle I did with the objects in the previous 2 paragraphs: nothing matches with nothing and a greater nothing would, again, match with nothing.

I don't know what is wrong with saying this, because as yet I don't have any idea what these statements are supposed to mean. I do not know how to interpret "There can be nothing more nothing than nothing."

3. Nothing is longer than A

4. Nothing is shorter than C

If Nothing is understood to mean the state of nonexistence, then these 2 statements are false. For what they're claiming is that "The state of nonexistence is longer than A" and "The state of nonexistence is shorter than C". But that is not at all what we normally mean when we say such phrases. Rather, what we mean to say is that "No object is longer than A" and "No object is shorter than B".

11. Nothing is greater (in terms of nothingness) than nothing

I'm not exactly sure what this is supposed to mean. Could you elaborate on this?

I should direct the OP's attention to this article by Behnam Zolgadr, which expands upon Graham Priest's Gluon Theory. In short, Zolghadr argues that Nothingness is the ground of being. So I think this is one avenue we can take to address the OP's concerns.

Perhaps it should also be mentioned that Graham Priest in his work entitled “One” posits Nothingness as a rather special kind of object; special in the sense that it is both an object and not an object.

So perhaps the concern you raise in your OP is not really so much of a concern after all?