I'm still not sure why they're not saving properly, and I'm not sure what you mean about it being specially coded, so here's a quick workaround to prevent guests from adding quotes.
in includes/functions_quoteit.php, find
PHP Code:
$quoteitpermissions = convert_bits_to_array($permissions['quoteitpermissions'], $vbulletin->bf_ugp_quoteitpermissions);
and below that, add
PHP Code:
if ($vbulletin->userinfo['usergroupid'] == 1) {
$quoteitpermissions['canaddquotes'] = 0;
}