The way you put it, King Kong could be propaganda. It spreads information for the purpose of telling a story. You're being too literal. (sorry if I sound like a jerk, it's just that I had a whole class dedicated to propaganda). Now, when has there been a propaganda film that isn't in some way political or biased in some way. This film doesn't seem biased in any way to me. It seems to just tell the story, and not really take too much of a side that it is incredibly obvious.