I disagree. I think what it comes down to fundamentally is coercion. You can call anything subjective so long as a person is not involuntarily subjected to the desires of another. Once that occurs, objectively it is no longer a question of subjectivity, because there is an individual with their own subjective experience and opinion being subjected to something else. Someone thinking "our species is a blight on Gaia" is subjective, someone deciding to help solve that problem and kill themselves is their business, someone deciding to solve that problem by killing others is objectively wrong. Chocolate or vanilla involves no unwilling participants, the analogy is flawed. You have an objective right to a preference there, you have no objective right to decide whether I should live or die.

Again, when left to consider only sovereignty over themselves and not over others as a prerequisite, the set of natural rights will be arrived at unanimously, regardless of culture. The only time there are disagreements are when someone wants to seek control over other people, and OK, so you can say "the idea that coercing others is wrong is a value judgment and subjective" but then you have no fundamental reason why slavery is wrong, you only have a mishmash of arbitrary rules and no guiding principle whatsoever. If you agree that owning people is wrong on some fundamental, principled grounds, then you can't come to any other conclusion than coercion is the principle. If you think owning people should be disallowed not because of some fundamental principle, but because of some pragmatic reason like democracy says so or something, then you have to accept that enslaving people is acceptable if the culture or circumstances deem it OK. But you can't have both, it's doublethink. Either we have natural rights are slavery is acceptable if it is fashionable at the time.