That's where the magic autoheal comes in.

But yeah, that would be a pretty big safety risk. It's a concept, these panels don't even exist yet. Actually it's not even sure if they'd even be possible. Safety only becomes a factor once they can start making them, I think.

If these concepts aren't constrained by what is currently (or ever) possible, why not make it capable of spaceflight? Or teleportation? Or a "submarine mode" a la James Bond's Lotus? Supercapacitor body panels seems positively dull in comparison.

No, because the capacitors discharge very fast. The problem is they want capacitors that discharge fast and have a high energy density, which means that during such a crash we could get an explosion or maybe even an EMP.