Comment by pclmulqdq

Well, "no child porn" is a comparatively black-and-white rule.

I would suggest you consider rules like "no racial/gendered slurs," which itself has caused a stir on Twitter recently when Elon Musk decided that "cisgender" was a slur. Most tweets that use the word "cisgender" to describe someone do so in a very negative light, often labeling them as "cisgender" with the implication that they are privileged, bigoted, and out of touch, but does that mean that the word "cisgender" rises to the level of a slur?