It is, indeed, unfortunate that Sarah Sanders was denied service at that restaurant in Virginia.
Last month, the U.S. Supreme Court ruled in favor of the business owner who refused to bake a wedding cake for a gay couple in Colorado. The basis of the Court's decision was that our First Amendment guarantees freedom of expression. Now business owners may feel justified in exercising that freedom.
Asking Sarah Sanders to leave a restaurant is particularly sad because the poor woman already has the burden of a terrible job: spokesperson for a truth-challenged president!