Danuser was in charge for all of Shadowlands though.Imagine you are a new writer starting at Blizzard right as the Sanctum of Domination raid is opening, what is it you would have to do?
Well firstly it's definitely too late to do anything about the ending to the raid, at best you might be able to change a non-critical ability or remove but not replace a voiceline.
So Bluevanas is already a fact at that point, nothing you can do to change it.
You are then further told that a cinematic is already being worked on where Uther aids Bluevanas.
Further you already know that the next patch will be Zereth Mortis, the raid will be the Sepulcher, and the final boss will be the Jailer. The zone is already close to being finalized as the zone developers are being moved to 10.0, and the assets are either already made, or close to being finished by a skeleton crew, so any changes have to be suggested now.
What is the process to fixing the story at this point?
Obviously you cannot salvage the lack of buildup, and Sylvanas' actions, so really it's more a question of how to soften the landing.
Then the raid is complete and players hate Bluevanas.
Then the Uther and Bluevanas cinematic comes out and players hate that too. At this point its obvious that players just hate Sylvanas. However there are also players who love her, so just removing her flatly isn't really possible, not to mention you have a book that is already advertised starring Sylvanas in the lead role.
At this point I think most writers would probably be close to giving up, just doing the bare minimum to make the ending as minimally divisive as possible, then jump to the next expansion and start writing that instead.