Let's make it even more complicated. Bob believes absolutely everything Al does, in fact his views are somehow even worse than Al's, but because he's not allowed to express his opinion nobody knows what he really thinks and he can only plan his genocide in secret.
Also, neither business is carbon neutral, nor do they plan to be. Refusing to buy doughnuts is implicit fat shaming, so you have to buy from somewhere. Due to a local endangered species deciding to build nests on the only road into town, no doughnuts can be shipped in from the outside.
I'm beginning to think that the only reasonable thing to do in the ridiculous hypothetical is to lease another corner on the same intersection and open up "Solomon Cohen's Pro-Semitic, Lemon-Friendly Bagel Shop and Delicatessen".
Is it okay for me to buy donuts from him then?