Doesn't this assume that the old pre-1969 theories about dust deposition over 2 billion years on the moon are still accurate? As the "YECs" (Young Earth Creationists) delight in pointing out, the expected large quantities of dust accumulations didn't materialize. There's very little dust, and the moon is a pretty "rocky" place.
Or would the helium-3 penetrate the surface rock to 2 meters? I'm no geologist. I'm just asking.
The dirt on the Moon is ground-up rock, made by the bombardment of micrometeorites on the Moon over billions of years. The helium in the dirt comes from the Sun, which implants helium, hydrogen, and many other light elements in the dust by the solar wind.
BTW, 3He is present, but in very minute quantities -- about 1 part per billion. However, this is enormously enriched compared to Earth. Still, it would mean moving a lot of dirt to get at it.