By definition
A woman cannot be a king. She can be a queen, but not a king.
shareit depends upon their point of view. If the Dahomey women were feminists, then they would not use the male form of a ruler, ie "king". They would say queen.
If they were not feminists and sought to be recognized as men (a political identity, not sexual) instead of women, then they could use the word king.
I have read some sources that indicate the Dahomey were not feminists at all. Are they reliable? I have no idea. Take a look at some of Martin Van Creveld's work. He is of the opinion that the women were not feminists.