I am not out to defend this scene or the writing of Halsin as I am not a fan of either of these inclusions in the game, but you are factually wrong. There is a prompt that you need to confirm after she says she doesn't mind sharing:
(Unless you have already learned about their proposal earlier at which point you can jump straight to: "I would like to hire both of you, and I hope my partner will join us as well", which of course entirely removes Shadowheart's agency in being the one to bring it up.)
There is nothing involving Halsin unless you click the dialogue option "Great, let's do it."
There is no need to misrepresent the actual events and interaction to make it seem even worse, as has been proven with the lengthy threads about this topic, people are upset about it enough as it is.
And to return to the topic of this thread regarding characters that are LGBTQ again, there is a female drow right there that Shadowheart shows interest in first (together with her male brother), hence she is at the very least queer.