I mean, you can't walk to the nearest working charger with a gas can, but if you have your level 1 charger with you, you can probably find an outlet nearby. Utility electricity is nearly ubiquitous along highways. Any sort of building near a highway is bound to have electric service; the question is if you can convince the occupants to let you charge for a couple hours.
If there's a big queue, you just wait. Same as if there's a big queue at the fueling station.
The guy replying to you said it's a pretty unlikely situation, so you treat it the same as other unlikely, but always present, issues that your car might have. You accept his answer.
Or you don't, and argue with him and say that you think he's wrong and it's going to happen too often, that's a fine reply too.
6% is likely enough to get you to another charging site, or a regular outlet for a slower charge. I’d expect AAA-style roadside assistance to deal with these scenarios in the near future, as well.
Personally I've never run into this but -- a long queue would be fine, the car doesn't eat up much electricity idling. As for charger status, I mostly use the Electrify America app for finding a charging station (i get 2 years free with my car) and it's good for showing charger count and availability. So, if a charger was out of commission, it would just show 3/4 available.
Google maps will actually show similar availability of various other company stations.
