This dumbass argument always seems to surface.
He can speak his opinion. Like Heath said there's no rules against it (unless you cross a line into outright hate speech) so he's not banned. HOWEVER, free speech doesn't protect you from the CONSEQUENCES of that speech. And if you use your right to speak your awful, moronic opinion and people condemn you for it and refuse to buy your products, more the better.
Where the hell people got the idea that "free speech" means you can say whatever you want and no one's allowed to criticize your opinion, think less of you or decline to associate with you I will never figure out.