I would tell the man that he should just take a class or read the Wikipedia on what a natural right is if he's so interested in it and using it to protect himself. I would tell him that commenting on it in this manner embarrasses himself and exposes that he has no education on the topic.

Any involuntary contract imposed on any individual is axiomatically immoral and unethical, as I've said below. There's no need to use such extreme examples.