How to hide the field date-of-death, in the biographical section, only for some users?
Reproducing the Issue
As this field is in the biographical section there is no way to control only the field's permission in RBP as this section can only be hidden by section and not by field.
RBP cannot be applied on some non-effective dated fields such as the field date-of-death.
Because the Date Of Death field is in the personInfo element, not personalInfo element, it is not effective dated. Therefore it doesn't have field level Role Base Permissions and cannot be seen in the RBP settings.
As a workaround you may apply permissions to the personInfo portlet to make all the fields under this portlet visible, or not, only to a particular target group.
KBA , LOD-SF-EC-LOC , Localization & Country Specifics , How To