Its is not legal but not completely preventable...
Yeah, I discovered that the only door leading to Metzger is clogged with militia. Might be a coincidence, but since they're standing in such a neat line, I doubt it.
I can't finish the briefcase quest, nor talk to Metzger to become a slaver and get Slavers rep that way for Small Gunsmith 3. Is it possible to get Slaver rep by killing critters?
Somehow it seems like actually killing those militia might piss someone off, so yeah.