Talking out of speculation... assuming CyberTruck gets this unibody (frame not body), it could help with aligning the rest of the vehicle with more precision. Maybe enough to make a watertight truck that could go into water? (Hopeful.) It would be so heavy, it might drive along the bottom of a nasty river. Video of this please!
The S protects us from airborn/fire debris, and now... CyberTruck protects us from Floods to keep you safe and dry.
All speculation, maybe real.
How prescient
I think this might also confirm a tapered rear from the roof, with covered bed for great aero.
Possibly lowering side panels to ease loading?