A 'morderator' sounds more like a post killer, than a person who keeps posts within reasonable limits. Maybe we need more morderators here. 
You see the problem we have here with people who don't have much appreciation of English. The member who vets the posts is called a 'moderator'. The inclusion of the extra letter 'r' makes the word look as if it is associated with the word 'mordant', which means cruel and criticising. Nobody seemed to pick up on this, and some continued with the misspelling.