I’d argue the main difference is that it involves a crime.
I’m not completely sure that torture itself constitutes a crime (though I’d be surprised if it wasn’t), but manslaughter/murder is. With few exceptions for medically assisted death, killing someone is a major crime. Presumably, we don’t want to promote people profiting from extreme suffering and death.
I also think there is a time and place for censorship (ex CSAM).
“Objectionable” is a subjective term, but “illegal“ is not.
I can kind of see what you are trying to say, but I don’t really agree with your conclusion.
I’d make the distinction that free climbing, while dangerous, is a recreational activity. I can reasonably conceive of people watching that for entertainment. There also isn’t anything morally questionable about it.
On the face of it, I don’t think you could reasonably argue that torture is a pastime.
All of that aside, torture is against international law. It is illegal in all circumstances.
From the United Nation Convention Against Torture:
For that reason, I would say the platform did have an obligation to de-platform it.
Arguably, the police should probably have put a stop to it as well.