We see that even as we normally tell a character that he or she shouldn't feel that guilt, we expect it. Or if not guilt, at least grief. Avon refuses both, and that's unusual.

I found it incredibly shocking when it happened. Not because it wasn't in character (it was incredibly, gloriously in character), but because, as you say, we are conditioned to expect a certain response from our anti-heroes when they commit these anti-heroic actions, and Avon just refused to go there.


Even more unusual is the fact that it never comes up again.

Yes and no. In any other show, yes. But B7 leaves ends untied just for the hell of it.