Hate to tell you this, but there had been plenty of gay characters in Treklit before Taking Wing.
Not "plenty," actually. We did get a very subtle, tentative portrayal of romance between two of the female leads of The Best and the Brightest
, but Keru was really the first prominent, recurring gay character in Trek Lit -- although of course Taking Wing
was his fifth appearance and came out four years after his first. (In addition to three prior Mangels/Martin works -- Rogue, Trill: Unjoined
, and "Improvisations on the Opal Sea" -- he appeared in Immortal Coil
by Jeffrey Lang.) There were probably a few others in that interval, but I'd say the majority of LGBT characters in Trek Lit came along later.
Certainly when early novels with Keru, including Taking Wing
, first came out, there were some readers who saw it as shoving a "gay agenda" in their faces because it treated gay characters' personal lives the same as everyone else's, but I would've thought that by now, nearly a decade later when such portrayals have become commonplace in both Trek Lit and beyond, it wouldn't be seen as somehow exceptional. I mean, it's been years since I've seen a post like that.