Well in my case with Murabitin Infantry right up there near the top of the unit prod file with siege equipment, it seems to me that the opposite may be the case. This could explain why my Turks reappearance was full of them, and why rebellions are always full of siege weapons, no matter how much I had altered the rebelling troops mixes. Removing them from rebellions was the only way to fix that. It seems that rebellions work from the unit prod list top downwards?