Actually if it's just a particular user - one way to trick people, rather than changing their user status would be to add some code in showflat/showthreaded where it does the bit for the moderator flag
if ($user['U_Number'] == xxxx) {
$postrow[$i]['UserStatus'] = "";
}
Which will clear out the flag that wsa defined for them as a moderator. You could do the same for name color etc.... Would still take some work, but not as much as trying to globally create a system to hide them.
