It might be the butler simply didn't stick around to protect the family when the murders began. Calliope didn't seem to know anything at all during the first timeline, so it would make sense she wouldn't specifically know anything about the butler either. However, if the man left at the sight of the first trouble, it would be enough. Of course it could be he did something unrelated to the catastrophe, like he was corrupt and fired much earlier. Or perhaps he was just generally nasty to the children, like he himself seems to think as well.