rebel,
I agree with you.
It's easy to say a head will make the book (and I mean B&C here), but it's another matter to have it officially measured and then entered.
There are indeed heads out there that could make the book but won't be entered by their owners. Nevertheless, a great many of the "yeah, that'll make B&C" heads won't. Perhaps most.
That doesn't mean it's not a wonderful trophy, but ...
It's not a book head if it's not in the book.