And Origin Story feels to a little...awkward and too convenient. I think transmutation from fanatical, upright, jihadist crusaders and guerrilla fighters to dishonorable, sneaky Bedouin desert raiders and amoral, atrocious world-reavers would be much more dramatic and poignant.
Edit: Furthermore, it could easily explain why over 40% of Dune Serpents turn to traitors, instead of relying on "because they are basically space Berber clans" rhetoric. We already have done a similar precedent: Morning Stars.