Odd that Gene got no money from the blueprints, though. His name is on them, after all, although not his signature. I assume that the abbreviation "APP'D: GENE RODDENBERRY" on sheet one means "approved by Gene Roddenberry". That approval is dated December 31, 1973, with the flattery "Chief of Design".
It goes back to the fact that nothing like this had ever been done before. If I recall, Gene and Majel thought the blueprints were amazing (the quote was something like, "We didn't know this kind of thing was even possible.") but they didn't think there was any commercial value to it.
They thought FJ was going to sell just a few copies at conventions and by mail order, the way Lincoln Enterprises had made only modest money. Since the deck plans had obviously taken a lot of work, probably for no reward, Roddenberry gave FJ publishing permission and "design approval" for free. And then FJ literally got rich on the blueprints and Technical Manual.