Once shutdown starts doing its thing, there is no guarantee that anything attempted to be started afterwards would run. If something was and it actually started, it could be killed at anytime.
I think a better approach would be to execute a script when you want to shutdown. The script would first display what you wanted to see at shutdown, then after that was up and running or done have the script initiate the shutdown. Thus giving you control over what to complete prior to shutdown.
I don't have Maximus so can't discuss how to change the behavior of the key you are pressing. If you need help with a generic type script to execute something and then start a shutdown, I could probably help.