There is an cool idea to prevent some players joining while the server needs to figure out some stuff.

So here is the idea behind it.

We need a new expression Variable like onHackedData in the server.cfg for example onJoinAttempt.
The Parameters we need for that is the SteamID and or the user-id.

So if onJoinAttempt is defined the Player is stuck in the Lobby or Loadingscreen until the Script in that returns true.
If it returns false the player is getting kicked.

Ref: https://community.bistudio.com/wiki/Arma_3:_Server_Side_Scripting

Would be awesome!