It depends on how he has everything setup. If he is connected to shorepower and running his battery charger to keep the batteries topped of AND he has wired his bilge pumps directly to his batteries, then no big deal. However, if shutting the switch off also cuts power to the bilge pumps, then I would not do this.
I'd press him further for WHY.
Roger, your fridge should run on AC as well.
However, I agree, the last thing we do at end of the weekend is button-up the canvas. The SECOND TO LAST thing we do is put a s'pak in the fridge so it's cold and handy when we come back the following Friday. (There's more in the cooler, but I'm not digging for my first beer when I get there)