Yeah, LW's brother had already clearly shown his attitude towards his niblings. (Which is, needless to say, utterly horrible._ I wish we could send LW rosefox's comment "practicality wins out over blood."

OTOH, maybe the LW was hoping that, deep down, family would win, or something. I personally think that was foolish, because I think people often overemphasize blood family over all else (see: everyone who has actively covered up a major crime a family member committed) and underemphasize family of heart, but, well, the heart has its reasons of which reason knows not.