I have two computers. One works as a Master, the other as a Client.
If I click "Disable Input Director" on the Client, it turns off and will no longer be available from the Master.
If I then click "Shutdown Input DIrector", the window closes, the tray icon disappears, but remote control is enabled again and I can control the Client from the Master again.
I consider this behavior not correct. After shutdown, the service must remain/become disabled.