Though extra code could be included to match a SteamID to the users listed in ULib.ucl.groups, even those not connected, for all intents and purposes, banning is intended only for those who are of utmost trust.
If you don't trust someone enough to not ban a higher rank, they should not be given ban privileges.
By default, it's given to superadmin for a reason...superadmin is the highest rank in Gmod.
