I would say 90% she doesn't work for a company that exercises Right to Work practices. Sears is based in MI, and most companies base their HR practices on California (strictest in the states) and neither are Right to Work states. This mean, if they wrongfully fire her then (you're right here) she has no legal standpoint. Even though the company doesn't practice these Right to Work laws, the court will uphold decisions made based on them (since it would be tried in Ma... although based on the text I was taught from, mass isn't a right to work state, might have changed since then though).
This may sound bad, but may be good. Courts are slow, HR departments are not (well, when compared to courts). So her company didn't break the law? But middle management did break company policy. I would be willing to bet that Sears has 3rd party arbitrators just for this type of protection (often called compliance services/numbers).
This is all conjecture, I would have to see some of Sears policies to prove it. The bottom line is, based on the HR trends today she has nothing to worry about. I would tell her to do what she has been doing and ignore pressure from management. most of the time these are empty threats, as they are getting pressure from the top.
I am working on my degree in HR right now, and I will be glad to share any help I may have to offer. I work for a company that has the same practices, and it isn't fun (starbucks is not a good company!). Tell her, whatever she does, just do her job right and she will be ok.