^The part of that I like is the reference to "the game of 'if it happened.'" That's basically the essence of tie-in writing as well as the effort of fitting tie-ins and canon together: it's a game, a fun creative exercise. People who worry about the "realness" or validity or authority of it, who use it to try to define hierarchies of inclusion and exclusion, are missing the quality of play that underlies it all. It's all just about exploring possibilities and testing ideas.
Heck, I've never felt there had to be a single "right" answer to what was acceptable as part of the "reality" or not. I've been putting together interpretations of Trek continuity and chronology for maybe 3/4 of my life at this point, and I've never felt that my version was the "right way" that anyone else had to follow; it's just my own creative exercise based on my own preferences and standards, and I assume any other person's would be different. What's more, I have little problem with changing my own chronology in light of new information; I've done so dozens of times over the years, sometimes in response to new canonical information or new books coming along, sometimes just because I reconsidered something and changed my mind. I know there will never be a final, right answer, and I don't really want there to be, since I enjoy the creative exercise of exploring different possibilities. That's what fiction is ultimately about -- not unshakeable truth, but exploring possibilities.