Why we use the condition !%client.isAIControlled() in missionLoad.cs

I feel confused. It is supposed that whenever a client connects to the server, its GAMECONNECTION handle is added to the clientGroup's internal list automatically. So why we are using the condition

if (!%client.isAIControlled())
 sendLoadInfoToClient(%client);

where client is

%client=clientGroup.getObject(%cl);

Can the clientGroup contains another client except the user whois ready to play the game?!

Thanks!

Note: I have not studied yet about ai. Maybe there is what iam looking fοr.