Who controls glibc?

Replace "it's offensive" with "it invokes an emotional response" in my point and it still stands.

I honestly don't think that reading the words that constitute the joke will invoke an emotional response in any significant proportion of its readers and, in the rare case that it does, they most likely have much bigger problems than the GNU manual.

Now if you genuinely think that a significant proportion of the population will be emotionally affected by those words, then by all means remove it. That just doesn't reflect the reality in which I live.