I believe in service dog that being said there is a problem in that all some one needs to call a animal a service animal is a note from a doctor. there is no certification process in most states and a restraunt owner can get into trouble asking for proof. Most of those claiming the need for service animals do not need there dog in the location but are doing so because they can. there is a big difference between a dog that is there to do a actual service for the person who has the dog and that of what is termed a emotional support dog. yes there might be a couple of emotional support dogs where they are necessary in getting the person out of the house but most of theses dogs are not that necessary. the law needs to be changed so that it is more then just a note from the doctor but a yearly certification that this dog has been trained so that behaviors that are not wanted from the dog like urinating and defecation is not happening.
service animals are god send for those that need them and the lady was out of line on how she reacted to the situation but I bet you that the dog in question was there because he was a dog lover not because he needed a service dog for what ever problem he was claiming.
https://www.ada.gov/regs2010/service_animal_qa.html
Looks like they need to do something not just be there for emotional support.