There did seem to be a deliberate effort to portray Garak as sexually ambiguous, beyond Andrew Robinson's acting choices. According to Behr and Robert Hewitt Wolfe, Garak's sexuality was discussed in the writer's room, but never really pursued as a storyline or outright addressed on the show because they didn't think they could sell it to Paramount. However, that doesn't mean they didn't do anything about it. Wolfe
had this to say in 2006:
The way I wrote him (and I think the way Andy so wonderfully played him), Garak was attracted to Bashir. He knew that attraction was not going to be returned (or even particularly noticed) and that was okay. He considered Bashir a friend and a protegee. There's nothing overt, there's no big flags waving or anything. It's all subtext. So maybe "clearly" is an overstatement.
How about, "It would not be wrong to interpret Garak as bisexual."
The subtext he speaks of is definitely there. Nothing concrete enough that it can't be up for debate, but still substantial enough that plenty of people picked up on it on their own, without knowledge of behind-the-scenes trivia to influence their read. It's an aspect of his character that sits in this weird limbo area that technically isn't "canon" but is intentionally present enough that I don't think it can be easily dismissed, either. That said, I'm someone who doesn't get hung up on what is or isn't "canon" or explicitly spelled out in the text, so it's easy for me to say that. The fact that Garak's intended sexual fluidity was never directly addressed or confirmed doesn't make that aspect of his character any less valid to me or difficult to reconcile with what we see on screen, though obviously YMMV.
RE: the article and DS9, I've said this elsewhere, but DS9 always felt like the queerest Trek to me, and I know a lot of other LGBT Trek fans who feel similarly. In part because of Garak and Jadzia, the saucy Mirror Universe shenanigans, and to a lesser extent the
fluid identity of the Changelings, but also because the station itself was a place where seemingly anyone could go to find a home and acceptance, regardless of how "othered" they were where they came from. The concept of "found family" isn't exclusive to LGBT people, but we nevertheless have a lot of experience with it as a byproduct of being disowned and ostracized by our "real" families and social circles, so this aspect of the show really resonates with me on a deep, personal level. And on the "just a fun coincidence" front, the carpeting in certain sections of the station resembles the trans pride flag.
Having been coded as queer does not necessarily mean a character is necessarily gay.
Maybe not in the most technical sense, but communicating that a character is gay (or, at least, not heterosexual) without having to state it outright is traditionally the objective of queer coding. It was a common practice in the film industry to get around the
Hays Code, when homosexuality was among the many listed "perversions" that could not be depicted in motion pictures produced by major studios and it's still a trick writers and actors employ today, relying on the audience's visual literacy and familiarity with stereotypes to get a message across that they either don't want to communicate in a more direct way, or feel that they can't be direct about without pushback from certain segments of their audience. It allows them to steer interpretation in a certain direction while still retaining plausible deniability. I find it a bit frustrating, frankly, but I understand why it happens and it's usually better than nothing.
At any rate, it definitely seems to fit what Robinson, Wolfe and co. were doing with Garak.
Garak playing the character as omnisexual, as Andrew Robinson put it, should have suggested possibilities, but not following them, we cannot know Garak beyond the actual romantic relationships he had.
He didn't really have any. The only thing we see that comes close is Ziyal, but he rebuffs her romantic overtures and seems pretty conflicted about the situation for whatever reason, and she dies before the relationship really has a chance to develop in any direction, romantic or otherwise. Garak never has any sort of concrete, mutually reciprocated romantic relationship in the show the way many of the other main and supporting characters do, a solitary existence which could easily be explained as a consequence of his past as an Obsidian Order operative, but it also plays into the kind of ambiguity the writers (and Robinson) were aiming to convey.
It could be argued that we can't make any assumptions about Garak's sexuality (or anything else about him we aren't outright shown or told about) since we don't see solid confirmation of it one way or the other. While I think this is an understandable position to take, I also don't think there's an absence of support for the opposite view in the show. It's just there subtextually, like so much else about Garak's character. Subtext can tell us as much, if not more, than exposition can, and it's an important storytelling device that lends depth, complexity and richness to characters and the worlds they inhabit. It exists as a complement to the text. It would be a mistake (and IMO, kinda boring) to completely discount what's between the lines, especially for a character like Garak, who, as Robinson once put it, lives in the subtext.