As a person who worked in retail, and managed and owned retail shops, I never allowed that nonsense to rule my stores.
Especially when I own it, that shop is my Kingdom, and I am the Emperor. What I say goes, and the very LAST person that makes decisions in my shop is the customer, and I am not at all afraid to say that directly to a customers face, and I have.
I have opened a shop with the product I have created, and I ALLOW you to enter and partake. If you can't appreciate the access to my product, and behave accordingly, your access to that product will end, and you will NEVER experience it again.
Do not EVER tell me "the customer is always right" in MY own shop. You enter at MY pleasure, and I don't care what you want.