Knowing little about the community and how they use the terms, I would interpret these subreddits to be about raising awareness that this is just as natural a way of life as any other.
There definitely is the reference to it's historical erasure and modern occurances, but the focus imo is on raising awareness. In which case, using it where others that see it , who are unaware of it's existance, is probably "free promotion".
[Edit] my english is bad... added some changes to grammar.
That is to say I personally wouldn't use a dating site themed around a reference for LGBTQ+ erasure. Though perhaps this doesn't represent everyone's opinion, and that's okay!
(For those out of the know here on Sappho/etc, see the subreddits /r/AchillesAndHisPal and r/SapphoAndHerFriend)