If there is one thing that can be derived from this book, it is that Japanese is highly "interpretable" and therefore, at the mercy of linguists.
This is definitely one of those books that shouldn't have been re-printed without some sort of caveat: "This book was first printed 15 (now 20) years ago. As you might imagine, things have changed a bit."
The "packaging" of the book (colorful cover, small format, easy to read layout, modern look) is a bit of a deception. This is a book meant to be read for fun! it says, when in reality, its original date of publication should really be taken into account by the reader. I wince at the thought of someone travelling to Japan with all of these examples filed into their head.