Snapedom

"It's always instructive to understand exactly what a person *means* by their words. We are all using English, but not everyone views words in the same way."

This is true, but it does not IMO resolve the problem. This is exactly the sort of thing than an author has to take into consideration when writing. It's probably not possible to make sure that every single person on the planet will get what you intend from a certain bit of text, but you can take steps to insure that the majority of readers do. JKR's personal notion of bravery has precisely zero to do with how readers interpret her text unless she communicates it effectively through that text. Which she does not really manage here, if her explicit statements about bravery have to be brought in in order to make Severus' moral redemption unambiguous. We shouldn't NEED her interviews in order to get the fundamental, meaningful points of her narrative from her text. It's her job as an author to give us those as clearly as possible *in the narrative.*