There is still quite a big difference between a fighter / future-head-of-the-household and a sexy matron.
Lacking a son, Shani will be Zaton's heir. Therefore she will either marry a politically favorable person (the Queen?) or marry someone who can take care of her affairs at home, same as what Zahra is doing for Zaton.
I always thought of Shani as his heir, probably because she chose to be the same profession as him. Also, she is the oldest. But that thought never crossed my mind. I guess I think Zaton will become ruler next to the Queen (or at least with enough influence for it) and Shani and the rest of the family will reap the benefits that come with that, while at the same time being whatever they want. In Shani´s case, she would be what Zaton is now and has been for years, a Stalker working for who is in charge.
But with Shani it's different. She needs to carve out her own place in Zetan society and it's unlikely that she'll do that by fucking people who happen to be friends of her father.
Shani can do whatever she wants, including fucking his father´s bff. I agree that she doesn´t have to do it and it probably won´t be what makes her famous as a stalker, but she can be what her father is. Zaton made a name for himself as Stalker and, in the meantime, was also fucking around with a lot of women. Why can´t she do the same? Unless we´re strickly talking about sharing her like she´s there at our disposal like the others, what stops her from wanting to join in if something is happening in front of her?
Besides, if Shani gets pregnant then it would be a rather big problem for her future, both in the short term (less chance to get fighting experience due pregnancy) and in the long term (less marriage prospects due to being damaged goods).
In this case, Shani has a mouth she can use if she doesn´t want the guy to cum inside her.
Btw, I hope all this talk about sharing Shani or not isn´t making you or anyone actually pissed. At least talking for myself, this is really just discussing it the scenario, nothing more. I´m not demanding anything.