They clearly have close to zero knowledge of what that actual decision was about. The decision found that it was unconstitutional (an infringement on freedom of speech and religious expression) to compel someone to produce speech that goes against their deeply held beliefs. The fact that a custom of a shop holds a particular belief is irrelevant to this decision, it would only be if the customer went into the shop and demanded that they produce something that went against their deeply held beliefs (in regards to the 1st amendment, this is generally confined to religious beliefs, so the Marxists might be in trouble unless they want to admit that it is a religion, which would be good because then it all gets removed from the schools). For example, if the shop sold custom bumper stickers, they would not be able to discriminate against a customer who happened to be a Trump supporter if that person wanted a non-political sticker made, but under this decision they would be able to refuse to make something that compelled them to produce speech that infringed on their deeply held beliefs. I don't think this is particularly good anyway, people should be able to discriminate how ever they want. Freedom of association includes the ability to associate with who you want and to not associate with who you don't want. So, it should be fine for them to put up a "No Trump supporters" sign, though how they would know what your political opinions are without asking you would be difficult to determine. In practical terms though, the "No Trump Supporters" sign is really saying "only people who hold the same political opinion as me". In the same manner, people should be able to put up a "No niggers" sign.