Putting aside the book under discussion in the article, which I have not read and know nothing about, I don't quite go with the argument, "if you don't like it then don't buy it" as if that is any kind of solution.
Firstly, if a book is unfairly attacked we might, based on those attacks, not buy something that we would, in fact, like, even admire. But if we buy the book to find out we could end up helping to make a book we find morally repugnant into a hit, thereby assuring that the writer will go forth and write more of the same sort of thing. (As someone pointed out above, stirring up a controversy is a very good publicity ploy.)
Secondly, in the case of a book that advances ideas we might personally consider dangerous (like white supremacy, or homophobia), not buying the book ourselves does not undo any harm we might experience from living in a world with people who have read it and thereby had their leanings toward that kind of thing validated and strengthened.
What we need is fewer people jumping to erroneous conclusions about a book they haven't read more than a small part of, and the solution is for reviewers, professional and otherwise, to commit to actually reading the whole darn book before forming conclusions about it and posting reviews or reactions. Or if they don't like it enough to finish—and I don't think anyone is under any obligation to finish something they don't like, it's what they do afterward once they have reached the decision not to continue that is important—then they shouldn't review it or write articles about it. Leave that to those who were able to read it to the end. I have seen lots of reviews for books I have read—and I am talking about favorable reviews as well as unfavorable ones—where the plot as described is so far from anything that actually appears in the story that is quite evident that the reviewer either stopped after a few chapters or else skimmed very lightly through to the end, and they are reviewing a book which exists solely in their own imaginations and has very little relationship to the book they are supposedly reviewing.
Of course there is no way to actually make that happen, especially in a world where so many people are desperate for attention and frantic to produce content which will gain that attention, that they don't really "have time" to finish a book before reaching conclusions and stirring up a furore.
One might even be led to think that social media needs to be more accountable and that their underlying business model might be part of the problem. 
