At some point moral values clash. The Egyptian Pharaohs kept slaves, fought wars of aggression, and had their living retainers sacrificed so they could continue to serve after death. We haven't kept sacrificing people, because we agree that it's just outright wrong.
He and I think it's also just outright wrong to hide archaeological details from future generations for the sake of the long dead. It sounds like you disagree with us, but the argument that we should respect their wishes just because they wished them is not a strong one, given that we reject some wishes on a case by case basis as morally repugnant.
What is it about this wish in particular that should be respected more than other wishes?