Wait, I thought he was just bullshitting his fans with that. He's actually serious? XD
Also, I don't understand what this has to do with bare metal construction of the Cybertruck and why that should present exceptional difficulties. DeLorean figured out how to make bare metal cars more than forty years ago, so it can't be that hard.
DeLorean also didn't use flat panels on the body. Though it might look like it at first glance, none of the DeLorean panels were flat, they all had a slight curve.
All metal panels are gonna flex a bit in the changing temperatures.
I'm not sure if you're trying to be sarcastic or not, but look closely at the DeLorean, none of the panels were completely flat, they all had at least a subtle curve to them.
I would think it was largely for sake of the style he was going for, plus even the most subtle defects in a perfectly flat shiny surface become way more obvious and stick out like a sore thumb.
Also, I don't think it's a really good idea to have what's basically a rolling mirror going down the road, at certain angles the sunlight will blind other drivers and pedestrians all that much more.
Your mistake was actually assuming that there is any discernible difference between a Musk statement he considers serious, and bullshit. They are the same.