https://workplacerightslaw.com/library/retaliation/construct...
My take:
The TL;DR is that it's just equivalent to getting fired. If you can prove you got shuffled out the door via constructive dismissal for reasons it's illegal to fire people for, then it's illegal. If at-will would've applied anyway, it's just a jerk move. Mostly it means you still get unemployment and can still sue for wrongful termination, even though you technically resigned.
What I suspect might be more of an issue, at least in CA, is that our at-will law has a "good faith" clause that basically implies you can't fire someone for a reason that would broadly be considered unethical in the context of an employer-employee business relationship. The classic example is canning someone just before they get their commissions purely to save yourself of the cost of paying them. My guess is that's one reason why Facebook, for example, is giving all their employees the mid-November vest even if they got fired first.
Constructively dismissing someone out the door probably takes away a lot of argument that you were acting in good faith.
If they promised these people that they could work remote and they invested in property then get forced to move, I actually wonder if it could open up the company to promissory estoppel (i.e., I had a financial loss based on a reasonable promise you broke, and now I want to recover).
The times I've heard about that cause in the past were exactly for situations where you moved for a job, then the job was rescinded. At the very least, that angle probably wouldn't look great in court during a wrongful termination suit.
(IANAL either, but since I work in CA I try to stay reasonably informed of the laws that affect me.)