I think that's kind of a cargo-cult answer. See http://en.wikipedia.org/wiki/Defensive_publication http://www.defensivepublications.org/defensive-pubs-faqs for modern approaches.
I guess by 'modern approaches' you mean (and the faq suggests) that making everything public and highly visible. The idea behind the "publish it as book" is that it makes it public, but not that highly visible. I guess it depends on the business requirements.
Btw. it was not clear from the site how much it costs. Is it entirely free?