It appears that the body frequently can adapt to absorb in another area, but there is no reason to take a chance. And even the most ignorant of doctors generally know that people who have had digestive surgery are especially at risk of B12 malabsorption. Blech!
Regarding storage, one can store perfectly and still become deficient. That is why people who have good stores and store well can take years to become deficient. If someone with excellent stores begins malabsorbing severely they will get no B12 at all unless they take very large doses or shots. After a few to several years they will be severely depleted if not treated with those very large doses or shots.
No, I don't think there's anything to the moons theory, other than the fact that B12 deficiency can affect people in many ways and there may be some for whom that is a factor. Moons or no moons, if one has other symptoms or signs I think B12 is an excellent idea.
rose