It's a cost/benefit situation. The cost of keeping the employee is very high in this case, even if they win the legal battle, and the benefit is probably unclear. The employee might be really great for the company, but it's difficult to quantify, and the moral cost to just let them go is low. It'll mean you and I will have a conversation like this about how crappy they are, but unless that conversation happens on the front page of WaPo or NYT it's just not worth caring about it. Haters gonna hate, and all that.
Most employers would see it this way, I'm absolutely sure of it. Even if fighting for the employee means they'll sleep better at night, it still would've cost an arm and a leg with little to show for it other than a feel-good sensation.
That's why it's so important for the AG to look into, and hopefully strike down on this shitty practice.