It most certainly is mature content. Profanity(particularly the f-word which is the case here) and any kind of graphic depiction of violence or death qualifies. I know plenty of people who would not visit the site because of the warning and who would be highly offended by what's there. I wouldn't want my kids or even my grandmother seeing any of that. Believe it or not some of us never swear(nor like to read or hear it) or look at disturbing images of any kind for any reason.
