Arguably it's a sign of a free society, free association and all that. What would a society where people and firms weren't free to boycott and disassociate from firms they didn't like be like?
A totalitarian world view is one in which someone no longer feels obliged to just offer their services or goods in free exchange, but to also insist that those they do business with also subscribe to their way of thinking.
These things are rarely related.
This is false shaming and participating in a false narrative.
This is exactly how totalitarianism takes hold.
A wedding cake baker chosing not to make a cake for a gay couple gets crucified and held legally liable -- yet the same exact behavior when an ad network chooses to do business with a company holding ideas with which they disagree -- that's allowed?
I personally think businesses should be allowed to discriminate for any reason -- the marketplace can answer that discrimination by not supporting those businesses.
I'll admit, your solution sounds nice, but how do you account for regions where the market supports discriminatory businesses and ostracizes marginal groups?