At-will employment doesn’t really factor in here.

The central issue is that Tesla gave him a job offer and based on that offer he resigned from his prior job. Tesla then reneged on their offer weeks later. The damages are the lost wages due to them not following through with the job offer after they caused him to resign.

I don't think that's really how job offers and at-will employment work. An employer can terminate an employee at any time (even before they've started) as long as the cause for termination is not illegal. "Employment contracts" are contracts, and a stipulation of that contract is the at-will nature of the employment.

I suppose the point is that's there's little difference, practically speaking, between this situation and being fired 5 minutes into your first day on the job.

I’d agree. You’d likely want to consult an attorney in that case as well, because barring some pretty extraordinary circumstances being fired 5 minutes into a job suggests the company didn’t actually employ you in good faith.

It’s relevant that tortious interference isn’t specific to employment, and thus isn’t really impacted by at-will employment. A company can legally rescind a job offer, or fire you 5 minutes onto the job. The civil claim isn’t that they can’t fire you, it’s that their employment contract was done in bad faith, and that they owe you for losses you incurred as a result of being a good faith actor who entered a contract with a company acting in bad faith.

You have absolutely no idea what you're talking about. Good lawyers usually give free consultations, especially the ones that see nothing but huge payouts for taking cases like this.

It's part of an implied contract however. Unless you know of some court cases where people lost because of it.

An implied contract that can be terminated at any time with or without cause