Earlier quoted context omitted.
Unless your friend lives in Montana, their employment is “at-will”. Which means at any time Tesla can change their mind on any aspect of the agreement and offer you a choice between a new contract or the door.
That’s not true. At will is almost never an excuse for violating contracts, employment law, or various discrimination protections. That said they can do it, but they would expose themselves to copious lawsuit liability.
Any kind of competent HR department will be able to manage a paper trail sufficient to dismiss at-will employees in a bullet-proof way, especially in a general business turndown.