These terms are only getting used more frequently nowadays, and I'm really happy that the book didn't just create autistic characters for the sake of it, but is well-researched and includes these terms. It reflects the recent rise in autism activism, which is not what psychologists tell us about autism, but what autistic people want.
E.g. last year I had a whole unit on childhood psychopathology in which the lecturer focused on person-first language, such as "person with autism", where most autistic people prefer otherwise, because I'm a gay man not a "man with homosexual tendencies" or whatever. It's part of my identity & not something separate, like a cold.