I mean, yeah. If someone doesn't like the sight of blood or death, should they work as a doctor in an emergency room? Probably not. Should they work for a software developer that has depended on that kind of thing for many years? Hm.
Why didn't he just say that it wasn't for him and resign?
Lol, this is simplistic thinking at best. You think Dr's love the sight of blood or guts? This stuff always has an impact on people's minds and its really a responsibility of the employer to provide proper support and access the wellbeing of their staff. Dr's also work years and years in a field which slowly attunes them to dealing with this, 99% of 3D artist do not spend their time watching decapitations.
Some of you really want to live in the stone age with your complete disregard of other people's well being. There are on going discussions in many jobs where this is required for example the humans involved in censoring social media content. It's a constant challenge and should never be dismissed as "well, just find another job", even the people seem ok need to have support systems for when/if cracks start to show.