Sounds like they're saying that since the distribution doesn't come from measuring or calculating the probability of something, it has the form of a probability distribution but isn't really one. Like saying 5 feet is a height that a person can have, but since I just made up that number it's not actually a person's height.
From the abstract:
"The Index captures technical exposure, where AI can perform occupational tasks, not displacement outcomes or adoption timelines." (emphasis mine)
The 11.7% figures is the modeled reduction in "wage value", which appears to be marketplace value of (human) work.
Well no actually it'd still clear to me that they mean the the multiplication of 3 different variables X, N, and D.
I don't think of it as eliding obvious operators. Rather in mathematics juxtaposition is used as an operator to represent multiplication. You would never elide an addition operator.
So X next to D still means multiplication as long as you can tell that X and D are separate entities.
I would wonder why they switched conventions in the middle of an expression though.
I assume they use N⋅D rather than ND to make it explicit these are 2 different variables. That's not necessary for 6N because variable names don't start with a number by convention.