This does raise an interesting question... if the Nicholas Meyer Khan on Ceta Alpha V audio drama ends up happening... would it be canon?
No, because he's not a current producer or showrunner, just an independent creator doing a tie-in. It's the same situation as Vulcan's Glory, say. A tie-in by a series creator is still a tie-in.
"Word of god"?
A nonsense phrase, because there's not just one creator, there's a team, and a story that a single creator tells outside that team won't necessarily be honored by the head of the team. Even the same creator doesn't necessarily limit oneself to a single continuity -- for instance, Rick Sternbach didn't try to incorporate any of his ship designs for the Spaceflight Chronology into TNG, but came up with new designs instead. Different works are different contexts, and a creator can adapt to those contexts.
And Mr. Bennett, this thread isn't reality: this is fantasy!
Yeah, but even so, it's important to define the terms of the question. When the thread starter suggests "making something canon," what does that actually mean? The first step in answering a question is defining its terms. It seems to me that making something canonical means remaking it as an episode or movie. And then it's not going to be the book, it's going to be something reworked and distinct from the book. Like when the Batman: The Animated Series tie-in comic Mad Love was adapted to The New Batman Adventures, it was mostly very faithful to the comic, but it made some changes here and there. Same with the "Holiday Knights" episode that adapted a Christmas special anthology comic (and left out the best story of the bunch). The tie-in books were adapted to the canon, but the canonical episodes were still somewhat distinct from the original books.
More to the point, what is the value of "making something canon?" What is gained by doing it? Canon is not a measure of a story's worth. It's not a reward for being good. It's simply a matter of consistency with other stories. So is the question, "Do you want this story to be acknowledged in other stories?" And if so, what difference does that make to the story itself? I think a story should be judged on its own terms instead of on the basis of things outside itself.