I am sure the small universe thing can be justified in universe, and has been, but it was at a level I didnt care for, a Williams, a Paris, a Kirk, a Dax, an alien character that was in like one episode of the series, a good chunk of enterprises crew now being on the Endeavour, when Reed gets his own ship, who does he appoint as first office, well another enterprise crew memeber (one whom I have never seen, in the series or books that followed, deisplay anything that shows he really deserves such a position).
As for the "small universe" charge, I think that overlooks the sheer breadth of the story I'm telling. If all these characters were on the same
ship participating in a single adventure over the course of a few days or weeks, then you could validly argue that it was guilty of small-universe syndrome. But the whole purpose of the book was to give an overview of the whole large
universe that the Federation encompasses and engages with. The novel features three ships having largely separate adventures, each of which could be its own self-contained work, as well as showcasing various political, military, and diplomatic leaders; and it spans eight months of story time.
I was required to keep the focus on the Enterprise
cast, because that's the banner the book was to be published under. I didn't have an option there. Now, if I'd forced matters so that they all ended up on the same ship again, that would've been small-universe syndrome. But instead, Archer is settled in as an admiral; T'Pol, Hoshi, Phlox, and Cutler are on Endeavour
; Reed and Mayweather are on Pioneer
; and Trip is off doing spy stuff. So that's eight characters distributed across four different settings. Plus Soval and Shran were in prominent political and military roles that brought them into play in the events of the story, though Soval's arc never overlapped directly with Archer's or Shran's. I had to feature familiar characters for the sake of audience interest and investment, but I tried to cast my storytelling net broadly enough that those characters wouldn't all be clumped together in one place and time, to make the scope of the story wide enough that it could reasonably encompass so many familiar faces.
As for Mayweather deserving a first officer's post, the Romulan War
novels did establish that he served on a number of different ships in the war, and clearly gained a lot of experience, even if those books didn't have room to highlight it. And yet Travis himself acknowledged in the book that he wasn't sure he'd earned the post. So I did at least lampshade the issue.
I used several alien characters or species who were only in one episode of the series, but I brought them back because I felt they were worth bringing back, that what those episodes set up was interesting and deserved followup. That's one of the things Trek tie-ins have been doing for decades: picking up on dangling story and character threads from the shows and films. The previous post-finale ENT novels were all focused on the Romulans, so that left a lot of other dangling threads that hadn't been touched, characters and ideas that I was curious about and motivated to do more with.