Allegedly, this recent material is all filler written after the main story. I'm told the anime is presenting the material in chronological order, whereas the novel just jumps right ahead.

But I agree completely. There's a pathetic excuse for "character development" for Kirito. This whole episode, we learned just one thing about him, his guilt about his sister/cousin. But even that comes out of nowhere, and serves no purpose aside from his motivation to help the girl here...which they largely rescind when it's revealed he was doing it for a completely different reason. I guess we don't even know if it was all a lie.