I think any business should have the freedom to refuse to trade with anyone they dislike, however irrational or bigoted their decision may be. I also think everybody else can denounce, ostracize, or boycott them for similar, or rational and non-bigoted, inclinations.

Nowadays I do wonder about how much integrity is involved in our post-modern social strife. While I like to think I'd sell on principle my bread to anyone, regardless of behaviour or creed -- there are some awful people with whom I think, honestly, I'd rather have nothing to do with if I know what they've done (a child murderer or holocaust-supporter or rapist, or someone who defends them, to go to extremes).

Banishment is a social tool that has been in use for a long time (forever?), sometimes with very good reasons, probably as a last recourse; I'll feel better when we have deliberate and explicit criteria for this method.

ps: I'm neither a "conservative" nor a "progressive" -- though I uphold thoughts that may be labelled by others as one or the other.