I'd wager there is a lot of untapped potential in hiring... "mentally divergent" people that enjoy watching this material. As long as they properly tag / rate / perform, there should be no problem with them.
Reddit used to have subreddits dedicated to gore and watching people die. There are serial killer groupies out there. An acquaintance of mine works in the judicial system and has no problem screening violent evidence. People who are not horrified in the same way by things clearly exist.
For jobs where normal people tend to develop psychological problems but that need doing, seems like we should be looking for people who are less likely to have those issues.
I say try because it probably isn't going to be easy.