From the unity-panel-service manpages:

DESCRIPTION  
    The  unity-panel-service  program  is  normally  started automatically by the Unity
    shell (which gets started as a compiz module) and is used to draw panels which  can
    then be used for the global menu, or to hold indicators.

How can the unity-panel-service be non-automatically started abnormally?
In other words, how is it arbitrarily manually started and/or stopped?

The manpage implication is that this can be done without stopping the Unity shell.

This answer seems promising:

Is it possible to restart the unity panel without restarting compiz?

but ... not. The process can be killed from System Monitor but it restarts automatically.

references:

• How can menu bars that require a right click be activated like Ubuntu versions <10.10?
• How do I disable the global application menu?