IIRC, the general rationale behind the 451 RFC was that this provides a means for a third party to communicate that they are censoring the content, presumably begrudgingly.
So, in the case at hand, GitHub is using 451 to communicate that a government censor has required that they take some content down, not that the company itself has decided to remove the data of its own volition.
It seems undeniable that this "feature" codifies censorship, making it more "acceptable".
"Oh, well they used the right code anyway"
back to approved activities