The swear is all very unenforcable and inconsequential in a mechanics sense. The game's not going to stop you from progressing if you refuse to drink the poison. So, how would the game be able to distinguish between a dialogue option that just gives you the poison and a dialogue option that gives you the poison but [DECEPTION]? Maybe you can fail? But then why choose the option that makes you fail, when you can choose the automatic success and have it make no impact on your character's development. I can't think of any specific examples, but there's a sense of deja vu in the inconsequential nature of the decision. I know that roleplay hardliners would like it a lot (and I respect that) because it gives you more opportunities to define yourself to a greater degree of specificity, but nothing really comes of it. I think you should actually have the option to end the game by suicide at any point, to drive home the impending threat (and horror) of becoming a mindflayer.
