Also that is the same reason why modders can't make custom GUI to servers.
that sentence completely false. making custom guis work for gamemodes is really easy and i did it on my bounty hunter gamemode.
Unfortunately not because that command is only client-sided and you can't make a client execute a client-sided command by the server.
this only stays true as long as you arent using client addons.
if you mean via a client addon, you can do:
commandToClient(%cl, 'function', %arg1, %arg2, %argN);
only works for clientCmd functions
example:
commandToClient(findClientByName("Zelwin"), 'SetBuildingEnabled', 1);
clientCmdSetBuildingEnabled(); is a default function, so it'd work on anyone
though,
commandToClient(findClientByName("Zelwin"), 'OpenBHHud');
would work only on me since atm i'm the only one that has the bounty hunter client addon