Human remains hold a certain sacredness and professional ethics and law (NAGPRA) require they be treated with dignity and respect regardless of the deceased’s ability to hold rights.

Evidence

Ethical Reflections on the Archaeology of Human Remains (Spanish National Research Council (CSIC))

corroborated: 2 independent passages support this claim
XREF: connects to: Small acts of decorum toward corpses matter more than practical logic — Julien Gracq, Balcony in the Forest, 483; We should respect corpses because violating them would be a violation of human dignity, and it is still a violation — What is the philosophical basis for respect of human corpses; Not all legal regulations regarding treatment of human corpses are spelled out in the language of dignity; some offenses express special disrespect against the deceased — How to conceive the dignity of the dead? A dispositional account (+6 more)

Moral and philosophical conceptions of dignity hold that a human being is entitled to ethical treatment in all phases of life and even through death. (similarity 0.86)
Not all legal regulations regarding treatment of human corpses are spelled out in the language of dignity; some offenses express special disrespect against the deceased (similarity 0.84)
We should respect corpses because violating them would be a violation of human dignity, and it is still a violation (similarity 0.83)
Congress recognized that human remains of any ancestry ‘must at all times be treated with dignity and respect.’ (similarity 0.82)
Posthumous dignity is not a right held by the dead but is the reason why the living have duties of respect and protection toward the dead. (similarity 0.81)
Posthumous dignity is not a right; the dead do not have rights and therefore no right to either posthumous dignity or posthumous respect. (similarity 0.80)
There are no practical reasons to show respect for the dead - you don’t get anything and the person is dead, so it makes no sense (similarity 0.78)