Marketing plot? I would assume that the book would be of interest to collectors of Castello pipes, and in that sense .... marketing.
On the other hand ... if you want to get a feeling / understanding of the driving forces at play at Castello and what those that work there and head the firm feel in their hearts ... then no, not marketing. It's more of an opening up of Franco's heart and beliefs. What aspects in life and pipes he holds as important.
For those that have met him, spent time with him, and have read the book, it re affirms that the man you met was not putting on a show. His enthusiasm about his company, his family, his team, and the end product, are genuine and sincere.
Sorry, but I really can't explain it any better.