When it comes down to it, no one would really do this.
To be clear, I'm not saying that Github censoring "retarded" is a human rights issue, but as long as we've gone off the rails let's see where the train comes to a stop.
A progressive making that claim would never take a bullet so that someone could fly the Confederate flag, for example. It's just not going to happen.
They may fight to defend the 1st Amendment, but that's easy because it's a proxy behind which exists all the specific instances of speech they would find horrible along with the speech they hold dear.
People making the claim probably mean the latter, but the wording implies something more specific, presumably for effect.
Charlie Hebdo did not publish, then get attacked for, content they themselves found offensive.
Then they didn't die to protect speech they were offended by. I don't know how much clearer this can be.
Let's see if anyone jumps to defend you...
What?
This. Is. Censorship.
It's not in any way a debatable point.
The dynamic that's going on here is that people want to endorse censorship while avoiding using that word.
I mean, that doesn't make it "evil", but a lot of people might say that censorship of any sort is a bit of a grey area. That whole "I disagree with what you say, but I'll defend to the death your right to say it" thing.