I wasn't able to read much of the linked article. Was the employee given the opportunity to keep her job and just wear a different mask?
Apparently, the employee decided she wanted to give her two-week notice since Whataburger had the audacity to insist she adhere to company policy.
Because she did that, they fired her, and rightly so. After all, here's a girl who's indicated that she feels, while on company time, that her beliefs are more important than those of her employer. She'd surely be a bit bitter about her employer not sharing her views, so it wouldn't be outlandish to think she might actually become a liability.
I used to manage a guitar store in San Diego. When someone gave their two week notice, we'd let them go, right then and there. We had thousands and thousands of dollars in the registers, and every salesman had access to every register. We simply couldn't take the chance that someone would do something nefarious.
Sorry to see you go, good luck, there's the door...