I'll admit "suggest" would be a better word here.
The reason why I'm enthusiastic about this seasonal indication here was because both prior water vapor measurements and radar reflectivity observations indicated a seasonal effect to the water content in near equatorial regions on Mars. These new results if they hold up would confirm those observations.
If I recall correctly the epithermal neutrons, which are given in the image, are more closely allied to the meter depth measurements of water content, while the fast neutron data measures the water within a few centimeters of the surface. If so, then the epitthermal neutron data should not be affected by a slight dust covering.
I'll check on this.

Bob Clark