Okay, so you're saying that, rather than take the chance (yes no matter what you say, it's still only a chance) that the mercs will kill everyone anyways, you'd let two completely innocent people die, one of which is only in this situation because you he came with you, and the other would have been a sex slave but at least a living one if it wasn't for this. You're really saying that?I don't think you get it. People are not logic-based automatons. People have killed for less or even just for the fun of it.
Your perspective is skewed as a reader. Your life wasn't on the line, and strangers seeming that way does not mean they are. Plus, serial killers tend to have charming personalities.