Yes, it is when an acronym is applied to something after the fact. When a word is taken, and an acronym is crafted to fit it. Like, "I'm going to call my album KOD [... several months pass ...] Hm, that's a lame title. It needs something extra, um "Kicking over Donkeys?" No. "Killing Other Dimensions?" Nuh-uh. Oh, I know! "Killing Out Darkness" It doesn't sound natural, like I struggled to fit Killing and Darkness into this Acronym... but it'll do."
I still feel though that "King of Death/Demons/Darkness" is too obvious to be it. The fact they want to do a contest makes me think that it's something out of the ordinary, otherwise it would simply be a race to be the first to make your official entry "King of Darkness" when the "contest" officially opens.
Look at MLK for example, normally it is "Company," but for the purpose of that release, "Kompany" was used. So it could even be something like (while still "obvious," is still not the first thing that comes to mind) "Klown of Death" or "Klown of Darkness."
I for one will be disappointed if after all the mystery, it does turn out to be one of the guesses that have been thrown out since "K.O.D." was first mentioned.