Works for me too.
Maybe your connection time (for testing) is below a certain limit to display your messages. Unreal (for example) has a setting in the set block for this: "set::anti-spam-quit-message-time <timevalue>"

To verify, try e.g.:
Code:
alias quit {
  if (!$1) { echo -sn Quit: no msg | .quit no quit message }
  else { echo -sn Quit: custom msg: $1- | .quit $1- }
}