I've often pondered about how Vulcans view gender and sexuality.
I think pre-Surak/logic, they may have demonstrated homophobia and transphobia, but modern Vulcan Society would probably be chill with it under the reasoning that discrimination would reduce a person's efficacy as a functional member of Vulcan Society. For instance, given a choice between allowing a person to contribute verses driving them to the brink of suicide, Vulcans would probably tend to lean towards the first option.
There could very well still be stigma (Vulcans are far from a perfect society; some may have views that it is illogical to have a romantic relationship without a child), but it's dampened by the logic from the previous paragraph.
There's also the Pon Farr to keep in mind. Not only would it be hard to fight a person in the Ponn Farr, but also you'd literally be killing them by trying to prevent expression of their orientation.
Another thing I didn’t initially think about is the Federation’s potentially great capability for transitioning people, considering how relatively simple it was for Bashir to transition Quark to being female then back to male.