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