Other than the toughness, I can't find a single reason why he would go with stainless steel.
Sitting here in India and contemplating about the CT, I would buy this vehicle in a heartbeat. It is so menacing, that it would give me peace of mind while driving on Indian roads. The vehicle by itself is an insurance against road rage :).
Sure, but if you do get hit, good luck finding someone who can repair it and paying their price...
Perhaps, but those aren't the exclusive, or even main, alternatives today.
800V charging? Great hard problem, strategic advantages
Stainless Steel body? Bad hard problem. No advantage in inventing expensive new precise manufacturing techniques, specifically to use a more expensive material for this one model. The market doesn't really value bulletproof body panels and stainless brushed appearances could be replicated.
Model 3 and Y are why Tesla is worth anything - solve a market need efficiently and effectively. X and S, Elon's passion projects, were terrible for the business.