Well, for the Hive, gender is probably really different than it is for humans. Comparing gender roles is really difficult when you consider both Savathun and Xivu Arath's different aspirations initially when coming to the Deep. Savathun was hoping to be a brood mother and Xivu wanted desperately to become a knight. Xivu easily placed into her role as a Knight, something that people would probably consider to be a role for males in our society, but the Book of Sorrows doesn't even break a sweat describing her desires. My point in saying all of this is that the Hive are divergent from humans in dozens of aspects. It's not far off to say that they probably have a completely different view on sex and gender than humans do. Saying that Oryx or Aurash were trans is kind of reductive to the alien nature of the Hive. I think that the Hive probably don't see what we consider to be gender roles as gender roles at all, but as jobs. Their bodies probably shift to reflect the needs of their environment, which is why I would disagree with you saying Oryx is a post-op trans man. I can see where you're coming from in that assumption, but I do think that the Hive are just too different from humans to compare like that.