I think the thing that feels really revolutionary about Gideon Nav's lesbianism is that she's not a lesbian in opposition to anything. She doesn't like women instead of men. It's just that her entire sexual world is female.

A lot of time having a gay character seems to necessitate a scene in which they confirm emphatically that they do not like the opposite gender. Gideon doesn't need to do that. She just talks about women all the time (and, lesbian character who is openly and unashamedly horny and actively pursuing women in general outside of once-in-a-lifetime romance, that's its own post entirely) and the absence of any mention of men makes it obvious that she's not interested in them.

And, as a queer person constantly having to explain WHY I don't want this or that, it's really refreshing to see a queer character who is so totally focused on what they DO want and not what they don't.