I think their position is that they are not against polygamy for others, but their construct is polygyny. Anyone who joins their family signs off on that construct (much like a monogamous construct) and if one of the females changes their mind, they are free to leave the group if they choose.
In my mind there is a certain amount of strength and wisdom to that approach. It has an unintended consequence effect that seems counter intuitive at first blush.
Yes it goes against the rigid authoritarian master complex that monogamy only, never divorce has fostered, BUT, every woman that is with him is there because she has bound herself to that relationship and you couldn’t get her to leave if you pointed a gun to her head. Not because he holds a vow over her head or leverages loneliness for life or excommunication from God himself against her.
Those are the types of women that even if the gubment drags their man off to prison for 5 years, they ain’t leaving. They know that finding another like him is next to impossible and they aren’t just in it for him. They are in it for the vision of intricately connected family and oneness and multi-generational prosperity that he has sold them on. They can continue his work without him hovering and micromanaging every little detail, and when he’s sprung, each one will have something to show for their efforts while he was away.
Obviously they are off a bit on the Nubian goddess thing, but IMO there is soooo much to learn from their “construct”.