Any business owner reserves the right to refuse service to any customer for any reason.
This can be abused by business owners, but most business owners don't exercise this right unless the customer truly deserves.
It's the same as kicking someone off your property for trespassing if they do something while visiting you that you do not approve of. Business owners, obviously own the business, and many own the property that the business is on. Others may lease or rent the building/land but it is still their business.
The customer is not necessarily always right. Business and companies used to be firm believers in this policy, but so many customers have adapted to abusing this policy just to get their way when, their actions/behavior are obviously unacceptable.