My reading of those prompt extracts would be that they are probably just intended to keep the model on the right track, ie if a user starts being aggressive towards the model it doesn't start trying too hard to appease the user in response, reducing the quality of answers in the process. If the model is being bullied into being "submissive" I would assume it is more likely to give the user the answer that they want over the truth.

Using a system prompt to steer the model's response to "abusive" behaviours doesn't necessarily mean you believe the model is sentient and can be abused.

Giving the model an end-conversation tool is interesting though. Why cut a (potentially paying) customer's session off? I guess it might be intended to prevent a "you can bully Claude into giving you instructions on how to build a nuke if you're mean enough" situation. Removing this in more recent versions might support this: maybe they feel the models are now better aligned and less likely to be so easily "socially engineered" like this?

Just spitballing here, to be clear.