If I was veeery bored and wanted a pointless internet fight I'd say you can kind of argue doing the slave stuff with Yellow is ethically questionable because of her past and employment situation... but that would dumb considering it's a porn game and the dev clearly wants the player to remember every character in the story is an adult clearly consenting to something they carefully considered with no pressure from Cyn. We don't have to worry about Yellow potentially being taken advantage of because the game creator's can and did decide it's not going to be that kind of story.