That's a huge oversimplification of the way the conversation would go. I think you're seeing the experiment like a logic puzzle that requires a totally rational solution, but that isn't in the requirements of the original philosophical question at all. If you treat this experiment more like a roleplaying game than a pure logic puzzle (and, lbr, roleplaying is closer to how people would respond in reality) then an emotional appeal would be highly likely to work, imo.

There would be hours of interaction where the AI could foster some kind of emotional rapport with the human. Plus the human would only believe the AI is evil and will get out because their employers have told them so. The AI could probably convince them that those other people are lying/ignorant, or don't know the truth about the AI's real altruistic motives, or are just selfishly profiting by keeping the AI trapped, or whatever. Like, if you were assigned to endlessly torture some apparently-sentient, communicative creature, would you really be able to continue torturing them forever, just because your supervisors told you the creature's highly realistic suffering was fake and designed to manipulate you? Would you trust your supervisors that blindly?