*Curiously, this is exactly how the sociologists/sex researchers who coined the terms cissexual and cisgender framed it - as healthy to conform to the sex stereotypes and sex role stereotypes associated with one's own sex.
So women not seeking to identify as trans were seen as normal, but only in the context of also conforming to gender norms. Of course there wasn't even a hint of a critical analysis of gender as the tool for the oppression of the female sex.*
Indeed. The gender ideology argues that everyone has an abstract gender identity (very doubtful), but that some are very lucky in realising that their identities match their biological sex while for others there is no match.
So the first group is now viewed as privileged, whether they are women or men.
The next step, then, is that sex-based oppression is erased, partly, because remembering it would highlight the fact that trans women have enjoyed male privilege and still might, and because maintaining gender norms is important for those who transition as they can more easily appear their desired sex.