Because individuals currently are allowed to be stupid & bigoted.
It's difficult to legislate against it without becoming increasingly authoritarian.
We were talking about the reasons for this being the case, and you said that it was because a business has a social contract. You now admit individuals have a social contract also, so the reason for differentiating them is clearly not that.
Now, imagine Queerspace decides to make a line of biscuits (yeah, I know).
Supermarkets stock them but the local corner shop store is run by a bloke who refuses to stock them. He stocks other brands of biscuits. In a conversation with an undercover reporter, he confides that he won't stock the biscuits as he doesn't agree with their agenda.
Lawsuit? Yes/no?