As a general rule, restaurant managers at these chain stores have to respect the brand. According to Applebee's:

"Employees must honor the privacy rights of APPLEBEE’s and its employees by seeking permission before writing about or displaying internal APPLEBEE'S happenings that might be " considered to be a breach of privacy and confidentiality..."

She was fired for breaching the the customer's privacy. And you don't normally do that (putting information online) because this kind of shitstorm can happen. They are probably sending a message to other employees, don't pull this kind of stuff or you lose your job. Now look at the shitstorm we have to deal with.

If she hadn't been fired, this whole thing would have been one obscure post on reddit and an outraged customer - this kind of thing happens all the time.

If there's any lesson for would-be entrepreneurs, it's about how to handle public opinion.

At this stage it really doesn't matter who was right and who was wrong (it seems clear to me both parties played a part), but Applebee's handling of this whole mess has been a study of what not to do.