Exposing your co-workers to snuff films at work is not necessary to create simulated violence. You don't seem to be getting that. Movies and games get made every week with gruesome depictions of violence that don't include watching the real thing. There is no comparison to those other professions.
You want to keep talking beyond that point, however, that's as far as we need to go morally and legally. I repeat, there's no need to even address your statements about individual choice or the artistic merit. The company is damaging its employees' health via a lax policy with an easily predictable negative outcome. If they don't change, they can get into trouble.
Really, what do you know what it takes for anyone to create the content of such violence as NR does or any violent content. Do you work in this field, do you have experience because I certainly do not. I have no clue and I am making no judgement because I do not do this work and never will. You are stating no one should have to watch this content and I ask the question, if a journalist watched violent content for their article, someone writing a book concerning certain violent content, a person making a documentary for a movie or show, you name it do you hold them also to the same moral standard. There are plenty of instances where people watch this crap for research into a number of various different medias why is your moral standard fixated on just NR as if there is some type of difference.
Only thing I know is that I have played the recent MK and those Brutalities and Fatalities are pretty graphic. I have watched some pretty violent Anime and I wonder how some of those people even come up with that stuff including all the gore. I have read books, viewed documentaries, watched horror movies you name it and from all of those medias people have watched the stuff expressed at NR for research. So no, I do not believe this is some moral issue different than any of those other fields.
What I do agree with is after doing more research on the situation is that NR would need to probably bring in someone to help with diagnoses of PTSD since its a condition that is harder to see and thus they would need to monitor employees who work more directly with the violent content to make sure they mental health is not being effected.