We all know there were no play testers (how could there have been with this many bugs?) or there were all too drunk or stoned to do their job. This information has to be inaccurate. No offense, Ratty.
Well rats, you made me go look it up.
Is the one unkillable character the Gun Runner vendotron?
No, you can kill him. One of our testers did it.
The one NPC you can't kill is Yes-Man. He just gets back up again. ”
—Jason Bergman
Perhaps they add the invulnerable attribute with a patch.
http://www.gamesas.com/index.php?/topic/1129506-so-the-one-you-cant-kill/page__p__16561233__fromsearch__1&#entry16561233