Yes, I think it should be okay to ask on this site.
If you find those questions distasteful, then you should also find any of the following distasteful:
- Murder mystery novels
- Dr. G - Medical Examiner the television show
- Questions about causing human extinction (arguably worse)
- Questions about genocide (arguably worse)
The topic itself isn't inherently distasteful. You can easily discuss such topics in a mature, reasonable, and empirical way (and in this case, clinical), and in many cases it can be considered an art form. Just because you subjectively cannot stomach those topics doesn't mean it should be disallowed. Allow the "welcoming" aspect to remain subjective - if you don't like it, downvote it.
I don't agree with your downvoting but I support your right to do so, but I don't think that downvotes should be called upon in order to discourage it. Let your opinion remain your opinion.
Secondly, worldbuilding doesn't necessarily entail that the world is nice and full of rainbows. I came to StackExchange because I feel at home with the empiricism, where personal feelings and emotions don't make the site feel suffocating. If we treat everyone with respect and good faith, then that means that we expect each other to treat such topics with dignity, and if that expectation is met, then that means we can be free to talk about darker aspects of reality with maturity.
The rest of the internet is already a cesspool of feel-good protection with demands for trigger warnings abound, and shadowbans for people who make anyone else feel the slightest bit of discomfort, which I feel is deleterious to a website about expertise, reason, and "just the facts."
In my opinion, you should downvote a question because it's a bad question. I do think that the question you linked is broad, but I feel that would be a better reason to downvote it, not its content.