I've seen similar bends in ponderoas up higher on the stem, when the top either died or the tree was topped. When a lower lateral takes over the top, they often have that same bend pictured.
I would be inclined to say it was from a natural event, then again, the prevalence of so many in one place is sort of baffling.
Nope changing my guess. Stem was broke low when the lower branch was about two feet long. Could of been a twister and the new leaders were on the back side of a small high wind event. So to say.