Silus was misguided, lost in his own awe of what his family had done.
So it was a complex choice:
Save a man's life and hope to save his soul, both of which he might lose later on in another venture like his attempt with the razor?
Give up that man's chance, damn him for his efforts so far and take the prize, whether to use it as Dagon intended - or to keep it from everyone and make sure it does no harm.
So far - Silus has had very little chance of survival, but I leave the choice to the character. If they help people, they will try and save him. Otherwise he's very much a dead man walking. Especially with one of mine - they were there during the Oblivion invasion and doesn't want to risk it happening again.