It seems that the Specific Permissions are called “Exceptions” in the code, so I was able to find the ppc_get_exceptions() function. Using this, I was able to extract the specific category permission:
?$args = array();
? ? $args['agent_id'] = $pp_group;
? ? $args['agent_type'] = "pp_group";
? ? $args['operations'] = 'edit';
? ? $args['for_item_source'] = 'post';
? ? $args['via_item_source'] = 'term';
? ? $args['taxonomies'] = 'category';
? ? $exc_arr = ppc_get_exceptions( $args );
? ? return $exc_arr["edit_post"]["term"]["category"]["include"]["post"][""][0];