The point is, it's not about the firing.

It's about an employment contract which involved compensation while an employee was working, where the employer backed out of that later and terminated the employee to keep from paying what are effectively back wages.

I am against suing to get one's job back, esp. here. However, suing to keep the unvested stock they took when dismissing you is a bigger deal.

Here's the thing:

1) Employee is promised stock for efforts

2) Company doesn't want to pay as promised

3) Employee is fired

4) Stock not paid as promised.

I don't think the fact that this occurs in an at will state has any major impact on the analysis.