eh, not how I see it. It's like, MC could tell Zahra to get on her knees, open her mouth, and then use her like a toilet if he wanted. That can be seen as "positive" empowerment, I guess? Because she's doing it for the very reasons you say, such as his desirability, etc.
Anyway, my point was more about how everyone can view these things differently. The feeling of empowerment can come from different mindsets. A certain fetish can do different things for them depending on their mindset/viewpoint of it.
Regardless, I'm in favor of the story's lore on why the sharing can occur in this society. I feel it adds more depth and shows MC isn't offering his women's services simply because he gets off on them being with other men.
My point is that, if Zaton tells Zahra to be his toilet, which I would label a
negative case, the authority goes from the top down in a sense. That is, Zaton orders something, he has authority over Zahra, and so she disregards her own desires and complies with Zaton's.
Just to give a vastly different example, if Zaton were to tell Zahra to give food to a beggar, which would be a
positive case, instead of doing as he says uniquely because of his authority, Zahra might instead recognize the intent behind the order (since it is more in line with positive traits, here charity) and
agree with it, and thus be driven to comply not only out of a sense of loyalty, but also because she herself comes to desire it, in a way.
So fundamentally, my distinction between positive and negative empowerment might be described as a distinction between
inspiration and
abnegation.
In this case, we might interpret Zahra's obeying Zaton in servicing Igor to be not her saying, “My husband has ordered me, and so I must do this humiliating thing,” but instead, “My husband wishes to show hospitality (in the Zetan fashion) to his close friend, and so I will do this for him gladly.” Those would be the two ends of the spectrum; in reality, it's likely a more complex middling situation.
It's true that there are many ways to frame the same act, in accordance with diverse fetishes, etc.