No he is refusing to make a cake for a gay couple

If he refused to provide groom&groom wedding toppers I'd fully support him but this is food not speech

Likewise I wouldn't expect him to write messages or make decorations he disagreed with

But in this case it's a simple case of discrimination

Literally in the article it says he offered to make them other items... https://www.cnn.com/2018/06/04/politics/masterpiece-colorado...

And literally the Supreme Court decisions stated that he objected to making cakes for gay couples on two separate grounds. To the extent that he may have offered them to make other items, it wasn't part of the basis for the decision, which was entirely about religious animus shown by the Colorado State commission that enforced the law in his case, and not at all about him not actually discriminating because he was willing to do business with gay couples, just not to make the specific cake they wanted.

The fact that something is mentioned in a news article about a court case doesn't mean that (even if it is true) it is part of the basis for the decision. If you want to understand the basis for a court decision, it's best to read the decision itself.