Sure no one has to read it, but you also don't need to give these people a platform to broadcast their views to an audience that is larger than the perpetrator's living room or pub.
Feeling unsafe around a psycho shouting at you on the street is reasonable, feeling 'unsafe' because someone tweeted a bad word is not.
I'm not even saying you're wrong but that's a terrible analogy.
How about "a sustained torrent of racist abuse". I can imagine some feeling unsafe in that situation. Can't you?
If we're talking ongoing, targeted individual harassment, that's different but still less immediate than a dude physically in your grill on the street.
Sure, post anonymously, and that's fine, but not everyone does (nor should be required to).
It's all roses at the beginning, but when they are targeted, your "look away from the screen" is looking distinctly weak.
I'll stop now. I can't keep up with your edits.
"Oh it is ok - their hideous torrent of systemmatic abuse calling for <ethnic group A> babies to be drowned at birth is totally A-ok because they said it on twitter so no harm done." No no no. This sort of thing cannot have any "get out" clauses where it is allowed in some circumstances but not others.