Violence for anything other than food or home is unnatural. The violence for sport/greed/pure evil in most games and media is not something that really exists in nature, and more specifically is not acceptable in modern society (while sex is).

‘adult’ just means ‘porn’. Even if it were one of the many, many Japanese games about molesting pre-teens it’d still be ‘adult’.

This is how you avoid getting accused of bias down the line: just allow everything, let the filters sort it out.