It only changes AFTER she picks up the hammer. When she first grasps it, it still says "he’. It’s not really a retcon.
In this specific context, it doesn’t quite make sense to change it to “they”. A female picks up the hammer, thus the wording changes to suit the gender.
Feminist wanted to prove women can make it on their own so marvel decides to strip a existing male character of his identity and mythos and give it to a women…that’s progress right.
Who cares? Thor’s power has always been tied to his hammer. He’s lost it a few times. Beta Ray Bill has taken it albeit for a short time and was mistaken for Thor. There have been “What Ifs” where Thor’s hammer was in the hands of other people, females included. Is it really so different now? Are you honestly that shaken up by it?
If this somehow shatters your universe then don’t buy it. Protest with your dollars.
Not yet. Rumor is that Fury whispered some sin Thor had committed and forgotten, so now that he remembers the hammer rejects him. I don’t know how that works.