This claim is made in the section titled 'Changing the boot password'. If you try to run the example, you get this error:
CALL SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY( 'bootPassword', 'Thursday' , 'Saturday');
ERROR 42Y03: 'SYSCS_UTIL.SYSCS_SET_DATABASE_PROPERTY' is not recognized as a function or procedure.
The correct way to change the boot password is documented earlier on in the section titled 'Encrypting databases with a new boot password'. We should remove the section titled 'Changing the boot password'.