I think this request could be quite useful so +1 from me.
My console is permanently in an area accessible to the public when the venue is open unfortunately. There is normally around 2 hours between end of sound check and the show where the console is unattended. It is always locked plus covered to make it less exposed, and less conspicuous, but the light bar does make it stand out – although it does look cool!
Being able to turn it off quickly via a single key, or even an option to automatically turn it off when locking, would be a great idea.