Alternate History and Real-World Insult

I'm deeply uncomfortable about the current debate concerning Patricia Wrede's new novel The Thirteenth Child, an alternate-history fantasy in which the Americas (North and South) are, for magical reasons, not settled by humans until the coming of the Europeans.
( this is unacceptable, say some, because it insults / excludes Native Americans )

This feels like a peculiar kind of censorship and I am uncomfortable, angry and disturbed by it.