I don't see any naivete there. He's not saying he's surprised that people are focusing on the salacious parts at the expense of the majority of the book; he's just saying, quite correctly, that it's an unfairly biased take on the work. Just because unfairness is predictable, that doesn't make it right.
This is not a book called "John Nathan-Turner - A Life Devoted to the BBC" or something similar.
This is a book called "The Life and Scandalous Times of John-Nathan Turner."
It's absolutely, absolutely
designed to make you go, "Ooh, what's the dirt in here?" He gets to have his cake and eat it too; he gets to draw them in with a salacious sounding title, get a lot of publicity from it, and then go, "Oh, no, no, that's just one small part in a larger book about more things!" If he truly felt this way, he wouldn't have named his book that or have been more vocal about the publishers giving it that title and bringing in attention he thinks is unfair.