It sounds like Kat was trying to get even with Dion for not sending her home, which could explain the careless and excessive display of symptoms and rant about her life. Or maybe she had a fever and was delirious.

Going out in public when there's a possible epidemic is a risk everyone takes regardless of the repercussions. It's up to you to take as many precautions as possible. However, I agree that if an employee is obviously too sick to work and does nothing to prevent spreading germs, the employee should not be there and should be sent home.

Under the conditions described in your letter, I actually think I would have left the store empty-handed.