Any retail store/shop, bar, restaurant, etc. can refuse to do business with anyone, the same as customers choose who to patron. If not, who dictates how one can run it. If I'm the owner, and told who I can and can't serve, who I choose, why would anyone be dumb enough to start it in the first place. The marketplace will dictate which ones survive and which ones don't.
Personally I have no problems with gays, and think it's dumb to refuse to serve them just because of that.
But it is any, businesses right to decide who their customer is.
Again, the market will decide.