I think the writer herself answers her own predicament at the end when she notes the difference between Elsa and Sandy (from Grease)--that Elsa changes her clothes/appearance only for herself and not for anyone else. The scene is about Elsa finally being able to be free from all constraint, and part of that is accepting that--godforbid!
The only thing in the article that annoyed me was this:
No."Even the umpteenth time through (and even though, in plot terms, this is the moment when she is basically assuming the role of villain),"



