I have found in the old ticket database some code snippet to enable censorship.
They should be both high to enable program of FLASH NVM location.
// Enable EPEE and BOEPEE
USIU.SGPIOCR.B.SDDRC = 0x60;
USIU.SGPIODT2.B.SGPIOC = 0x00;
while(UC3F_A.UC3FCTL.B.EPEE != TRUE);
UC3F_A.UC3FCTL.B.CSC =1;
UC3F_A.UC3FCTL.B.PE = 0;
UC3F_A.UC3FCTL.B.SES =1;
UC3F_A.UC3FMCR.B.CENSOR = INFORMATION_CENSORSHIP;
UC3F_A.UC3FCTL.B.EHV = 1;
So yes, please make sure you execute the set censor process from RAM.
Also check errata sheet for the device you are using, there are some mentions about censorship.
Unfortunately we cannot offer comprehensive support for these legacy family (MPC5xx) since we do have no expert.