dthunt is right. The prominence a female character has in the storyline before her death doesn't really affect whether it is or isn't a fridging. What matters is whether her death is a narratively appropriate end to her story and character arc, or whether her death primarily serves to motivate a male hero and further his heroic journey. (See http://www.feministfrequency.com/2011/04/tropes-vs-women-2-women-in-refrigerators/ for a full discussion.)
Hermione's death was a textbook fridging. That's not to say that it's automatically offensive or sexist or whatever: like TVTropes says, tropes are not bad, tropes are tools. But yes, Hermione's death is a classic fridge death.
Your summary is a much better definition of 'fridging' than the one which appears on TV Tropes and should probably be added there, since TV Tropes is where I went to look up 'fridging' whereupon I was much puzzled by the accusations. But as the application of your definition deals with future events within HPMOR, rather than things which have already happened inside the story, I cannot comment further.
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 88-89. The previous thread has passed 500 comments.
There is now a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)
The first 5 discussion threads are on the main page under the harry_potter tag. Threads 6 and on (including this one) are in the discussion section using its separate tag system. Also: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18.
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically: