In defence of the XKCD comic - context is everything. Whenever someone asks me what the trackpoint is called, that's actually what I link to them. I've not got one complaint about it being NSFW. Most people in addition, either call it the little red eraser thing, or mouse NWORD - so sanitising the question of the word may have made answering the question harder.
While the action taken was a suitable middle ground, I don't think it would be obvious to most people that the comic was NSFW. In addition, one of the two names (the one starting with n) is something I often came across working with auto mechanics - for example, I found greasing NWORDs on trailers, and it was not censored out.
I'd think that unless the actual intent was to post NSFW language maliciously, we really can't and shouldn't go overboard on PCness. In this case the use of the NWORD was necessary in establishing context, especially if you didn't know what a trackpoint was called - editing out after it was answered made it easier, I suppose, but if someone complained about the NWORD in the question, I would have found it odd.
All in all, I suspect that was actually an appropriate use of the NWORD and other body parts, and any reasonable individual not using a dumb word flter would have noticed. If so, it's not as much a problem of offensive language, as slightly bizzare workplace policies.
Edit: removed references to giggling uncontrollably - see edit log. Now read on.
More importantly, Safe for work (SFW) is variable. Anecdotally, apparently this is SFW for me. Hypothetically you obviously find it NSFW. Anecdotal things actually happen.
I'm saying context is what's important, and both of the 'offensive' terms used are common and customary terms for a on-keyboard pointing device. I personally prefer to call it the red eraser thing. More importantly, I do not think self-censorship with the intent of keeping a question or answer to fit in with a arbitrary value of work safeness is productive. Do we apply $cultural values of SFW? Do we ban the mention of buns because it would disturb discordians? Or do we do the sensible thing and actually read the over all context? This is an edge case and one where a significant portion of people who regularly use the site wouldn't have an issue with the original posts I suspect.
What would be the effect of reading XKCD at work? In a geeky environment, nothing at all. In one less so, maybe. On the other hand, in context there's very few situations where a comic would be a suitable answer to a question and this is one of them.