Maybe, and likely, given all the other cuts they made, but as far as I know it's not actually known, which is frustrating. That said the article calls it an SUV and isn't exactly riddles with facts, so.
The pictures from the cybertruckowners forum show something on the surface causing discoloration, like road grime or dust disintegrating in the rain, not like rust forming on metal. I've restored a few rusty stainless kitchen knives in my day, absolutely abused ones, and even cheap stainless doesn't rust like that.
Eventually, yes. Especially around salt. Not in 2 days though. Maybe take the trash click bait article with some of that salt.
I'd love to see someone sacrifice a body panel and do a 3.5% salt solution test like knifenerd does.