You got a few downvotes, but you’re not wrong. Another issue is if you have tags for everything except being straight, then it sort of implies that being straight is the default “normal” option, and everyone else has to go out of their way to designate themselves as not normal. It’s something that should be left up to the users to choose, instead of having a default.
Sort of like if you had race tags for everything except “white”, it would imply that being white was the expected norm, and everyone else has to mark themselves as outside the norm. Or for a more forced-binary example, what if a game had a “woman” tag, but no other gender tags? It would heavily imply that the expected default is “man”, and every woman (or really anyone who doesn’t explicitly identify as a man) has to self-select.
That being said, it’s a queer game made by queer devs for queer people. They can do whatever the hell they want with it. Not every space is meant for straight people; Queer people have often been required to go out of their way to form their own communities and spaces to avoid judgement from straight people. Demanding a “straight” tag feels a little like a straight dudebro walking into a gay bar and getting pissed when dudes flirt with him. No dudebro, you’re the one who is wrong here, because you have literally every other bar in town to go to instead. You don’t need to encroach on the gay bar, because it’s likely the only place gay people have that is truly “their” place.
Alternatively: people have gone out of their way to foster a space where LGBTQIA+ people feel comfortable. In a world full of heteronormativity, this is a bubble where they can truly be themselves. It’s one of the few places where a gay dude can flirt with another dude, without the fear of being punched in the mouth just for being gay.
And then a straight guy walks into the gay bar, and starts a fight when another dude tries to flirt with him. He starts ranting about how it’s not okay to assume he’s gay, and that he feels oppressed for being straight. He wants the heteronormativity to extend even into LGBTQIA+ spaces, despite the fact that he could go to literally any other bar in town and not have this issue. Instead, he has chosen to make a scene at the gay bar, because he’s upset it’s a gay bar.