I actually like that she got to keep her powers in the movie, but I understand your reason for disliking that. IDK, I guess my interpretation is also that she was able to reach that part of her brain, and then being able to learn things at her own pace didn't mean she could no longer reach that part of her brain or something? More scifi-ish than fantasy-ish, at any rate.

We could probably do a book interpretation of the fic as well, though: in order to access her powers again, Matilda would have to "dumb herself down", and we all know how little she liked that. One very good reason to keep the job internship right there.