"If it's REALLY ice, then you could easily distill 99.9% with a simple crusher and solar furnace."

Just above room temperature and 1/100th of earth atmosphere should cause the water to vaporize. But I don't know if this would get 99.9% of it. Or even 90%

For example:
"The method involves drying a soil sample in an oven (105oC [221oF] for 24 hours) to determine the soil moisture content."

So if you want dry soil and put it in an oven for 24 hours. Why are they cooking it for 24 hours, instead say, 4 hours?
And after 24 hours, does it really get all the moisture out of it, or simply enough for any practical purpose?
And cooking lunar regolith for hours could expensive.

If you cook dry sand in a oven for 6 hours how much water is still in the sand? And after 24 hours, how much water is in the sand.
If you had oven in a pretty good vacuum [1/100th of earth atmosphere would much better than most] and cooked fairly dry sand for 2 hours how much water is in the sand?

Let's put in ppm. If you have 2% per volume,
that is 20,000 ppm. 99.9% of it is 19,980 ppm leaving 20 ppm of water. Has anyone on earth made sand this dry?

And would a finer grit make it harder to remove 99.9 % of the moisture?

Mars has 210 ppm of water in it's atmosphere and Mars is pretty dry.

"The maps look interesting - very localised concentrations in specific shadowed craters. "

Yes, it's very interesting, certainly an improvement over the original data