The free market always makes the choice. If a business owner is doing something objectionable, he will no longer get business.
That's why all those segregated lunch counters never survived on the free market, right? Oh, wait. Also, how does this shop keeper believe he can tell who that's shopping at his store is gay? Will he question any two men who come up to the counter together?
No he can't and he won't. He's making his statement. But how can you deny that people who find this sign objectionable, like me, would avoid shopping there? It's just common sense.