I believe we need more information on both the cases where needling regrowth was kept and those where it was lost: maybe there are factors that we have not considered, or we are not aware of.
In general, I tend to believe that Androgenetic Alopecia works, in some aspects, like cancer, even more, like aging. It cannot be stopped or eliminated or reversed forever (at least for now).
But we can slow it down. Alas, that won't work for everyone equally - but that's what ultimately sucks with alopecias. If every man balded at the same age, give or take a few years, then we would accept it without too much chagrin, as it happens with wrinkles or other more democratic signs of aging.
But for the same reason, any visible regrowth is worthwhile even when it is temporary, because it kicks the can down the road, at a point where it becomes relatively less heartbreaking, and, fingers crossed, more treatable thanks to scientific progress.