My thought is there is never a reason for a store employee to be rude. A simple response of, "I'm sorry we are closed" would have been the appropriate response and I would have hoped the OP would have accepted that. I understand that people want to get home to families, plans etc. at the end of their work day. I have to confess that about 100 years ago in high school and college I worked in an Ice Cream/Diner type place and sometimes a bus would pull up about 5 minutes before closing. Sometimes I immediately turned off the lights. The next day I always sheepishly confessed this to the owner... fortunately he was understanding and laughed.