Gender Identity Terms in LCSH

I have two categorical questions as I am working through LCSH related work part of my cataloging course in my MS-LS degree.

In the case of Gender Identity and sexual orientation based terms, there seems to be an over specification on some terms and an underspecification on contrastive terms. I would like to know if I am reading the assumptions correctly.

For example: There is a LCSH term for Flight Attendants. However, there is also a term for Gay Flight Attendants. Linguistically, this split (marked and unmarked) seems fairly common. So my questions are:

1. Am I to understand that the LCSH term "Flight Attendants" excludes "Gay Flight Attendants", or am I to assume that Flight Attendants is a super-ordinant category one sub-class of which is Gay Flight Attendants (with potentially hundreds other sub-classes left unnamed)?

2. Why were terms related to gender identity and sexual orientation not established as free-floating "modifier terms"? It seems that to be overt about gender identity and sexual orientation in a term one should have "Straight Flight Attendants" to contrast with "Gay Flight Attendants", but the gender identity and sexual orientation literature suggests that this is not a two way distinction so where are all the other terms? Are there minimum requirements for the addition of new terms (15 works or something like that, but then how does one go back and re-classify materials like this)? It seems from an entity management perspective that making Gender Identity terms free-floating allows for the fewest number of entities with the greatest amount of descriptive power. The gender identity and sexual orientation modification pattern applies equally well to the religious identity terms. Consider: "Muslim Flight Attendants".

With regard to #2 above is this the difference between a noun-noun construction and a adjective-noun construction?

A couple of Academic Papers on the subject: