When people change their last name, newly-created references to them do in fact use their new name, even if talking about old events. That said, it's not really

When people change their last name, newly-created references to them do in fact use their new name, even if talking about old events. That said, it's not really an analogous situation, because when people change their last name it's generally in response to a life event, and so references to them that predate that life event weren't inaccurate, they're just old. Transgender people who change their name aren't doing so in response to a life event, they're doing so because their old name was never who they were. It was a name forced upon them by their parents and society. Chelsea was always a woman, it's just the world didn't know until she came out. The name she used to go by was never really her, and continuing to use it is supremely disrespectful to her. Or to put it another way, if you have a friend that comes out of the closet and announces they're gay, do you ever talk about "when they used to be straight", or do you recognize that they were always gay and you simply didn't know?