Why would you hide comments about Slenderman? It's not against any domestic or international laws. It's not against rules either. It's not a curse word. It's something fun that people like to read about and watch videos about. Remind me again why you'd hide such comments?
Oh no, there's nothing wrong with dear Slendy being popular. That doesn't mean I have to like it that Slendy-fans have these interesting conversations about who saw him too though on my page, without making any reference to the photo itself or about my own Slender-free concept for the photo.
So just as people have a right to leave ten comments saying nothing but 'SLENDERMAn!!!@#!!!!' on every single photo of mine, because they like it, I have the right to hide them, because I don't. Gotta love the fairness of this world ^^
Feel free to invite people to comment about Slendy on your photos. I'm afraid the fact that I'm hiding Slenderman comments is none of your business though