I was not making a claim to what it IS, regarding genre and content, I was remarking on what it IS regarding to genre and the CONCEPTION of that genre by generally un-knowledgeable and judgmental people, and how that effects marketing strategy.
I'd agree with you entirely that horror doesn't not equal necessarily blood-and-gore. However, given the North American nearly ritualistic release of horror movies with tons of blood and gore, often in October, it's just a general perception of the genre (horror/"slasher-flick"). And by calling something "part horror genre" that makes marketing games and movies with lots of blood and gore easier to be unopposed by critics in markets with large youth demographics. Particularly the console industry, where, while COMPLETELY UNTRUE, is the perception that the user base is dominated by those 13 and under.