Experiential womanhood can be a difficult enough thing to quantify in our world, let alone a world where magic of all sorts is omnipresent, material reality is mutable through the manifested power of gods and spirits, and ritually recognized gender-variance. If you're defining experiential womanhood solely through a reductive and biologically deterministic account, that both denies the fundamentally social reality of womanhood and seems like a flattening of the diversity Glorantha offers, especially for player characters who often follow the inherently transgressive and norm-breaking path of heroes. In that sense, relegating those people who exist outside of the Orlanthi all to a singular "other" bin subverts the mythic and social diversity of the setting in a way that is ultimately unsatisfying to my reading, but every Glorantha varies. In my reading, these definitions can be expansive, and the power of heroquesting assures that expansiveness is rarely limited.
Professional historians, anthropologists, and sociologists are trained to avoid whiggish, eurocentric, and presentist perspectives: history and culture aren't a linear teleological progression towards a nebulous ideal. The ancient world was a pretty terrible place in a lot of ways, but it's relevant to note that many of those societies were far more diverse (if not always fully accepting) in terms of gender and sexuality than those Victorians who codified many of the tropes about the ancient world. This goes doubly when you break outside of the western fixations of pop history: gender variance is not a novel thing and was long tied to certain shamanic traditions. It would be pollyannaish to presume any of these cultures had modern sensibilities, but flattening them into a teleological line is a mistake. While most historical societies weren't nearly as tolerant as the Orlanthi, if we actually want to understand how those societies operated (or how the Orlanthi might), it's important not to project our biases and social constructions directly onto those societies and let the social realities of their cultural and ritual roles speak more clearly for themselves.