They should look at it more like a toke to the users. Backend should be token/$. This ideology would allow them to open up simple apps (sex related) that run on their blockchain.
For instance: A small camera app that makes you earn Sexcoins with selfies send to friends. The more sexcoins earned they unlock features (like adding filters or stickers to your selfies). And so on. Never in the app frontend mention sexcoins.
There is zero reason for them to use some 3rd party coin as a token. It's nothing to create some "token" that the users can buy for money and they want to tie the value of that token to a far more stable currency like the USD as opposed to something volatile like a crypto coin. This is already established practice in both the porn (primarily cam sites) and game (primarily f2p) companies.