To understand much of our language, Gnorts would have to already be aware that our words and symbols gain meaning from how they're used, and you couldn't, for instance, determine that a swastika is offensive (in the west) by its shape alone.
In this case, the term "colored people" gained racist connotations from its history of being used for discrimination and segregation - and avoiding it for that reason is the primary principle at play. There's also the secondary/less universal principle of preferring "person-first language".
A person who actively discriminates in hiring against black people but doesn't call anyone a slur is seen as more virtuous as someone who doesn't discriminate, yet uses the slur in jest. The first behavior is seen as more excusable than the second, although an actual reasonable moral judgement makes it evident it's not.
What in the world are you talking about?
A report comes out, turns out that a certain HR person in company A hasn't hired a single black applicant since they got there.
At the same time, a video comes out showing the equivalent person in company B saying the n word in passing.
In this situation, it's maybe considered that the person in A might be racist, while it's completely assumed the person in B is.