I have to give you a 100% on this. It is the Business that suffer. It is their establishmnet and should be their choice. if they live in a place that has Smoke Nazis as the average citizen, they probably would not stay in business very long. But if they live in a free country, then the diners can decide.
In fact, did you know that in most places a Business can already decide? And yet most still allow smoking. Why? maybe because it is good for their business? There is no law saying a restaurant cannot prohibit smoking in the whole establishment. Just economics saying they should not.
But is it not the right of the business owner to decide? How would you feel if they decided you could not do certain (legal) things in your own home, just because you may have some guests over?
My Wife is alergic to smoke, and if we are seated too near smokers, we have 2 options. We can ask to be moved, or just not go back. that is OUR right.