Yes, that's what I've heard, as well. As I understand it it's rather like "Indian" for Native Americans -- some people do use it as a self-descriptor and some of them get (understandably) very annoyed about being language policed about terms for the community they belong to; nonetheless, many other people within the relevant communities do not use it, prefer that no one else do either, and in the case of the g-word it's widely considered a bad slur. So it's a "don't use unless you're talking to someone who uses it for themself" kind of thing, to my understanding. As I am not Rromani etc, I therefore don't use it either, but I don't know what the politics behind this book's subtitle are. (I've read it, but years ago.)