Is there something specific about this that you think might have crossed a legal line? Just saying, "hey we have too many employees so we hope some of you quit, and since we actively want people to leave, we aren't going to do anything with employee-satisfaction in mind and in fact might even make life worse, hoping it drives people out"--why would that be illegal? It's shitty, and I'd probably be looking to make their wishes come true by finding another job, but it isn't--and IMO shouldn't be--illegal.
Also, remember that it people quit, that's great. if people are laid off, the company has to deal with UI claims and possibly severance, too. So by signaling that cuts are coming they can usually get some people to leave voluntarily and thus save the company a few bucks.