"Its in his business best interest to see that other restaurants ban smoking too."
Ah, the "free market benefits from government intrusion" argument. If he feels it is in his best interest to ban smoking, then finds that his competitors are doing better business than he is, it would be in his best interest to go back to allowing smoking.
Your comment reaks of communism.
If he feels it is in his best interest to ban smoking, then finds that his competitors are doing better business than he is, it would be in his best interest to go back to allowing smoking. Banning smoking decreases costs, especially labor and table turnover. If revenues stay the same then its profits increase. Revenues will stay the same so long as smoking is banned in all restaurants.
Therefore, its in a big businesses best interest to ban smoking. In the long run his bottom line is highest.
He has a duty to his shareholders to provide the largest profit possible. If getting legislation passed enhances his profits then he has a duty to lobby as hard as he can for that legislation.
This is simple capitalism at his best.