The amount of water distilled sounds quite good too. I think 1.5 litres/m2/hr. I guess you could have separate solar and water things but maybe it's cheaper to put them together.
Without the cost analysis of the split system, I also question the study. Sure it’s cool technically, but dollars drive everything.
Of course cost is going to determine whether this is practical to deploy, but products don't spring forth form Zeus' head fully formed. We should expect they'll need time to iterate on BOM cost and performance.