I protect SoP.
My reasoning:
1st - I received this via PM. I assume 6 other people did, as well.
Hello, my most wonderful spectators or participants.
7 of you have received this message.
I humbly request that you post in my thread with all haste.
Refuse to do so, and you die.
They will choose one of you who must die.
Tell them what I have told you here.
Remember - you are the only ones who count.
Aha!
Incog is setting up a string of posts by various cops/civilians.
2nd - Incog's favorite number would appear to be 3, given that the reference to numbers in the title, "3-Word Story" is obviously 3. (Kudos to SoP for noticing that!

)
3rd - Incog said that we would somehow determine the victim in his hint, and he said in the PM that "They" would choose who dies. Who? The cops? Or the posts? What would be the point in posting, unless it were somehow relevant, eh?
4th - SoP was the third person to post after Incog's announcement.
Therefore, I am certain that SoP is the intended victim.