Just repost it here, and add a link (coming from someone who does NOT know the forum rules front to back).
Regarding breaking the campaign setting:
Well, losing key NPCs is a risk you take when you set PCs loose in that campaign world. However, people in power didn't get there by being careless. The more important someone is, the more bodyguards/security that person has.
Have you ever tried getting into the White House? Without an invitation? Much easier to get into a World Trade Center...
Also consider that as the magic/technology level increases in a campaign setting, there more resurrection options a main NPC has.
"You tried to stab me? Ha - I was wearing a bracelet of instant-teleport. Thanks, high-magic setting!"