That's precisely the sort of behavior Tesla's idle fees are intended to prevent, or at least reduce, right? I'd be surprised if anyone does that, and shocked if anyone does it more than once.
In addition, Google Maps says it's a 25-minute walk from the supercharger to the outlets. Even if we're generous and say 20, I think it's beyond the range of "convenient to walk to while charging" for a lot of people. And unless you're charging from low levels to 100%, you'd hardly be able to get any shopping done before the car is done charging, if you factor in the round-trip walk.
Having said that, I was eyeing the various eating establishments that are closer to the supercharger for a potential future trip...
+1 for Matts Fish Camp - only 8 minute walk.