Regarding BDtP, the revised TSOY book says: "This not only allows her to zoom in the imagined camera on this conflict, but is the only way to permanently injure or get rid of a major named character controlled by the Story Guide."

Am I missing somewhere else that it talks about not being able to kill SGCs via conflict resolution?  How do you manage this?  Are players simply not allowed to say: "I attack the guard with my spear. If I succeed, I want him to be dead." 

Dont get me wrong, I like this.  Its hard to have any kind of real "bad guys" when they players can often quickly take them out via Conflict resolution.

I believe they're allowed to kill guards with a normal conflict. But not Rodrigo, head of the Watchmen, who may or may not have played a role in the poisoning of Lord Bancroft. Like the quote says, "This not only allows her to zoom in the imagined camera on this conflict, but is the only way to permanently injure or get rid of a major named character controlled by the Story Guide."

And, yeah, it pretty much comes down to them not being able to name killing the major character as stakes for a simple conflict. They can name it as the takes for a BDTP conflict, though.

Notice that it also says "getting rid of" and not "killing" a major named character.  No, "I stuff him in a chest and bury him 100 feet in the earth so that he never escapes." intents in the Conflict Resolution either.  You can stuff Renaldo the Magnificent into a chest and bury him but if you want him to never escape if'd have to be BDTP.