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".
Like the paragraph quoted above: it's just so blatantly obvious what's wrong with turns like "considered particularly enlightened", or "there are no underlying principles" that I find it hard to believe that the text as a whole sounds so friendly and convincing, unless you stop and think for a second.
I wish I could write like this about whatever mush is in my head.