Slurs are generally less effective once they've become mainstream.
Go spend some time on 4chan, and this will become clear--'-fag' is used as a suffix/term-of-art, and basically doesn't even register on the radar anymore as being said with any seriousness.
"Goddamn" and "Christ" were once quite serious business as well.
Of course they're less effective once they've become mainstream. As you mentioned, many slurs gradually lose any hateful meaning, and I'm sure the term "faggotry" might be becoming a bit less offensive over time, but seeing as how it's still used by many people in a hurtful way, it's not unreasonable to expect some people to be upset in situations where it's less clear. If someone disliked a comment using the term on 4chan, I wouldn't assume they disliked it for the term, but this isn't 4chan.
It's almost certainly a complaint about the use of a slur, not about the underlying complaint about the buttons.