I can't believe for one second that Paramount Pictures. Which has been historically notorious for both "creative accounting" and extreme penny pinching on their properties. Didn't wring every last possible cent out of anything that had "Star Trek' on it. They owned and still own the copyrights to everything "Star Trek". Paramount puts serial numbers on their one-sheets (posters) to track them if anyone tries to sell one. Back when I managed theatres, I knew of some that were sued by Paramount because a couple of posters ended up in a comic book store.
Studio management and practices change over time. And this was in the first half of the 1970s, before Paramount woke up to the fact that STAR TREK would become a financial goldmine. There was a little window in there when the studio thought STAR TREK reruns would peter out and die soon. Franz Joseph was just very lucky to have such a good product and not be asked to pay any licensing fees on the blueprints.
After that, when Paramount knew there was money to be made, Ballantine Books used a technicality to avoid legal hassles over the Technical Manual. The book itself never says Star Trek. The words "Star Trek" appear only on a separate card that slides out of a clear plastic pocket on the black slip-cover, which itself is not part of the book.
This trick somehow evaded the licensing question because the book itself was just about "Star Fleet," and Paramount had not yet registered that as a trademark.