It’s Perfectly Legal For This Tennessee Hardware Store To Refuse Gay Customers

In Tennessee, there's nothing illegal about refusing to sell screwdrivers to gay people.

There is also nothing illegal about not patronizing his hardware store either.
If you choose not to give him any business and he refuses business - so be it, you can spend your money elsewhere and he can be deprived of increased revenue.
Now should you choose the give him THE business ( i.e., the  middle digit of your hand in an upraised position, etc.) for his asinine 'views', well, he deserves them and can do nothing about it either.