Re: Let's Discuss the Romulan Bird of Prey!
Well, The Making of Star Trek
was written after "The Balance of Terror", so - having no evidence indicating otherwise - I have to assume that Stephen E. Whitfield (hopefully) talked with the producers and what they said made its way into the book.
So it looks like a premise change.
"The first duty of every Starfleet officer is to the truth" Jean-Luc Picard
"We can't solve problems by using the same kind of thinking we used when we created them." Albert Einstein