The argument isn't that "black" is offensive, but rather that it's connotation with negative things is.
To use your The Office example, it would be as if "bad" hackers were called "Mexican hat" hackers, forbidden lists "Mexican lists", etc.
(Except not, because "Mexican" only means a kind of person, whereas "black" means many things, but that's the argument being made).
We use constructs like that all the time. Or are we going to start saying "red lights" are offensive? Or "yellow lights"? Around yellow proceed with caution! Red means Stop! Danger!
How about "Dark rooms"? Should we avoid that? Change red-black trees to green purple?
Or hell, lets rope the electrical engineers into it. How dare black be the color of the negative cable. What's white? Oh, ground? You mean where everything ends up going? Heavens, pull the wiring out!
This moral panic reminds me of a quote from C.S. Lewis.
>"Of all tyrannies, a tyranny sincerely exercised for the good of its victims may be the most oppressive. It would be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated; but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience. They may be more likely to go to Heaven yet at the same time likelier to make a Hell of earth. This very kindness stings with intolerable insult. To be "cured" against one's will and cured of states which we may not regard as disease is to be put on a level of those who have not yet reached the age of reason or those who never will; to be classed with infants, imbeciles, and domestic animals."
Truly, in these Times have the moral busybodies had their Jimmy's rustled.
Sometimes I wonder whether some of this ridiculousness is put on by foreign influence operations. Because I could not imagine a more effective strategy to hand the election to Trump. Most people I know are rather appalled at the orwellian censorship of the current movement.
Do I ever have a new word for you. Have you ever heard of the term 'yellow peril'? Color coding is a remarkably easy and efficient way to encode racial stereotypes and spread propaganda.
Nowadays the association with said color is lessened (though some elements still appear among racists) but it seems rather ignorant of history to ignore the uses of color coding for racial dogwhistles.
THAT's what makes this an argument that fails a "sanity check".
(They proposed "incoherent" as an alternative to sanity. Well, people can be insane and people can also be incoherent, and both are negative labels when applied to a person. What does the one improve over the other? I say nothing.
It's a mixed bag. I don't see anything wrong with at least starting to steer the great ship of inertia away from "him" and "man" for everything when we do have perfectly servicable, not ridiculous, not confusing alternatives without even resorting to hir/sie/etc. It hurts no one to say their in place of his. Even "person-hours" is fine even though it's an extra syllable. In fact the new term is simply the truth. It's simply the more accurate communication, which all these supposed rationalists should be all for.