I'm really glad you chimed in on this. Thank you for the clarification in regards to Bruce Jenner as well as the more universal rules and...
While this seems strange at first, you have to realize that this person has always been their chosen gender, even though they weren't necessarily able to show it.
... when you put it this way makes sense. I think it's the peculiarities of the situation (we always saw Jenner in such a masculine / athletic role etc) that make it feel strange and make it seem like we are rewriting history. This is especially apparent in instances where Jenner is not the direct focus of the sentence / moment:
The American media in 1976 were infatuated with Jenner, as much for her looks as for her athletic prowess. Time magazine called her “beautifully sculpted” and described “the waning light shining on his flapping chestnut hair” as she crossed the finish line.
In my mind, the American media in 1976 were infatuated with, and commenting on, a male, even if she identified as female. It may be nuanced, but there is a difference between the media describing a male athlete like that vs a female one. I'm not saying we handle these cases in one way or another, just...yeah.
I think another reason I may find myself grappling is because Jenner is a public figure that is removed from me and my personal interactions, not a close friend who I actually interact with. I do find that I refer to my IRL friends as "he" or "she", even when referencing them in the past. ie: "It was so funny when she did that" even if, at the time of the event, they presented as male.