A Hermione who risks all against Dementors "to help Harry" is not nearly as interesting to me as a Hermione who risks all against Dementors because they're evil regardless of Harry.

We'll all help our friends. Pick any evil person in history -- they had friends. If they're a political leader, they had lots of admirers.

The fic itself has Harry make the point that if you're only interesting in helping an "us" and not a "them", that's a pretty weak sort of good that easily turns to evil.

I think in a fic so full of extraordinary characters, Hermione deserves to be extraordinary enough to do awesome things even for strangers, even when she doesn't think her friends will benefit, because a world without dementors is just better.