That's one way of looking at it but what Kazuo Ishiguro is talking about is.
It's not really things that might meet with public disapproval that are the thrust of his message but the genetic makeup of the authors themselves.
I don't think the idea that one's identity influences how your words may be taken is a new concept in publishing either.
Your article includes a reference to J.K. Rowling, who decided to publish using initials rather than her real name because she felt that writing what she did under a clearly female name would not meet with success.
I don't think I'd be going too far out on a limb to guess that for much of publishing history, being a black writer would hurt your ability to be published and read in a number of markets and genres.
I'm looking at this from the perspective that:
!) The publishing industry as a whole has always gatekept on a number of arbitrary points including the confluence of identity and content
2) Consumers of literature and critics have always done the same.
3) Authors, with the exception of a tiny few end up making McDonald wages amounts or worse when it's all said and done, and that includes many "Bestselling authors". I don't think of publishing books as a livelihood issue for authors on much of a meaningful scale.
4) Old school book publishing is a dying field.
5) The best authors generally showed boldness and wrote their truth despite what society would think of it or how it fit into the current fashion of publishers. If individual authors lack the courage to write true and good works because they're afraid people might say mean things on Twitter, they're not cut out for the field. Yes, it takes a thick skin, always has.