In addition to the points in my other comment, I'll note that there's a rather easy way to apply real-world implications to a fictional scenario. Attack qualities of the other player's fictional representative that also apply to them in real life.

For instance, if you were to convince someone in the context of a roleplay that eating livestock is morally equivalent to eating children, and the other player in the roleplay eats livestock, you've effectively convinced them that they're committing an act morally equivalent to eating children in real life. The fact that the point was discussed in the context of a fictional narrative is really irrelevant.