forgive me if i'm not clear on the concept

But if the seven people ahead of him/her in line are all dead or incapcitated, why would we reward the Secretary of Homeland Security for doing such a bad job of protecting them by making him/her President?

Or is the idea that whatever took out everyone from the President down to the Attorney General is something the SHS is better equipped to handle than the Secretary of the Interior? Not that I want Gale Norton as President any more than Michael Chertoff, I'm just asking.

Maybe I'm looking at this from the wrong angle. Maybe if you can't keep the President, the Vice President, the Speaker of the House, and so on down to the AG safe, your punishment is that you have to be President.