We see much worse than that all the time. We go to movies that portray horror, torture, murder, depravity, slavery, etc. There are books that contain all those. There are tattoos on people that depict scenes of death and satanism. We put these in their proper place and tolerate them, many people even enjoy them. There are some efforts to keep them out of the public eye and away from children, but it's quite easy to see incidental advertisements, posters, or discussions of all of them.

We should treat social media the same way. There should be a way to filter what you don't want to see, that's your choice. But we shouldn't try to stamp out people saying what they want, or decide what other people should filter for themselves.

Most people who say things like you quoted, aren't killers, i'd guess that most of them aren't even racist. A good fraction of them are just immature, or social outcasts, that are desperate to get a rise out of people. If we could all turn down our reactivity, there'd be less of a draw, for those troublemakers to spew their nonsense.

What we should be the most on guard against, are the unintended consequences of trying to censor this stuff. People shouldn't have their political and social voices limited, just because a relatively few people are disruptive like this.