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.
Being a contract worker is the alternative to being an at-will employee. Employment law, nor discrimination protection law, have anything to say about dismissing at-will employees who are surplus to business needs.
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.
That’s untrue, lay-offs and not for cause terminations have all sorts of protections and implications for the employer. The employment law body for not for cause termination is substantial, and discrimination law absolutely applies in not for cause termination - if they laid off all their pregnant and black employees you don’t think there would be liability?
If the firing is discriminatory, then yes obviously discrimination law applies; I mean, that's kind of obvious isn't it? Everyone knows that "at-will" doesn't mean "you can be fired for illegal reasons".
A well-executed termination of at-will employees because of a change to the business environment is basically never going to fit into any of the exception categories to at-will, again assuming a competent HR department. Pretending otherwise doesn't help anyone.