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".
I politely asked for a fact-check on it in the comments section, as I otherwise enjoyed and agreed with the substance of the post. He both removed the claim in question and my comment.
I was unsure of how to feel about this. Those who had already read the post online or still had the original in their inbox were left with the misinformation from what they may consider a trusted source.
I believed it would have been better to edit out the false information, leave my comment, and reply with clarification on the editing and why.
Likewise, this practice of dynamically-edited online content is actually relevant to the topic of PG's post and the role it plays in replacing the traditional constraints on printed media.
In addition to those who received an older version with the misinformation, a critical aspect of determining what is true is determining who to trust, since there is far too much to be known for any one person to determine it themselves. Silently editing your own writing to respond to good criticism of it leaves future readers less informed about your own trustworthiness.