Merana got shoved aside! And her appoint was also meant to be non-threatening to Rand. And the women I. The camp at the time of her appointment where busy trying to establish order. This the Strongest, the Salidar Six along with those about the same level stayed with the camp.

The Hierarchy applies to every part of AS life, just because deference may be shown to a Sitter or Keeper etc does not mean that women with higher standing aren't considered first for these roles. Just like we see with the Tower embassy. The women in charge are the strongest for the relevant Ajah ... Merana was the strongest for the Grey therefore she was placed in charge. As soon as her authority was challenged by a stronger woman she was ignored.

Elaida was to strong to be challenged for the role and despite a huge lack of skill in the arena got the job she wanted. Realistically any number of AS would have had vastly more skill as an Advisor than Elaida, why didn't a Grey like Merana get the job?