Does anybody remember the 'super straight' thing that was around a few years ago? It was meant to distinguish straight men who would exclusively consider biological women as potential partners and straight women who would only consider biological men.
I gather it was done deliberately, and not wholly seriously, to make a point and shine some sunlight on the 'enforced' attraction to somebody based on their 'gender' and not their sex i.e. a lesbian who doesn't fancy a transwoman is being phobic, hateful and horribly prejudiced.
The argument was that, if we're now only allowed to choose partners based on 'gender' and not sex as 'standard', then this makes 'super straight' people and their proclivities 'different' from the imposed 'norm' - hence the inclusion in the alphabet soup, albeit slotted in at the beginning, in recognition of the sheer numbers of 'SS' people when compared to L, G, B and T people.
Absurd as it is, I think it would actually make more sense to include 'SS' people in the group of sexual orientations than it does to include T people. Not saying that T people deserve any fewer rights that anybody else, of course, but why not have a separate group for T and NB people and their different considerations, rather than arbitrarily lumping them in with LGB people? If it's being repurposed just to group together all minorities and/or oppressed people, why don't we add anybody who isn't white to it as well, and disabled people? And why not women?
By way of analogy, there was a croquet club that was established in Wimbledon in 1868 - which later expanded to include a different sport as well. It's still an extremely famous and popular club, and annual tournament; but the original croquet element has rather been forced into the background and public obscurity.