A person has died. Do not use rest in peace at all. Say at peace or something. Rest in peace is a prayer related to the idea of Heaven being an endless Sabbath and rest. It is based on Christian judgementalism - where it is assumed that the deceased deserves no rest and God must generously grant mercy.
Slaves were buried with that prayer.
For victims of oppression use rest in power. This accepts they are
gone but wants their power to ripple on and live after them.