I think a simple comedy movie should not been seen in anyway as a so called "act of war" and it just seems like preventing its release is another step closer to losing more freedom in the world because of corrupt and violent regimes. Since North Korea's nuclear capabilities only have a range as far as Cuba it looks like Kim Jong Un has no chance of starting World War Three therefore I see no reason why it should not be released since it looks very likely that Kim Jong Un is bluffing but if he isn't and starts a nuclear war over its release he will be remembered as the guy who started the war the destroyed the world over a movie.
However North Korea has had nuclear weapons since 2003 and still not used them. North Korea is also aware that army wise The United Nations(particularly America) would destroy him if he starts world war three. He has nothing to back his statement and if he started a war over the movie he knows it will end in his death.