Yeah, I am not sure if how I would do it would be an appropriate way either, just an idea. I like that the first conflict of it was an internal one as the players choose how to deal with such an issue, and then an external one as they put their plan into action.
If they are just cold agents of death, this shouldn't be an issue for them, but it could be if they have the right recovered memories.
I really need to read more of the book. :)