Probably prevent sending packet to server might not keep you from getting client error because there might be cases that other player's machines detect you are inside the wall, they all send notification packets to the server,many notifications from different machine might be a good proof that lead server to disconnect itself to your machine(Kick you out). I don't think CF developers depend entirely on client side in terms of connecting and disconnecting to the server.
So that being said, our wall hack can be patched forever