If the baker had said "I'm all booked up for that week/ month" there would have been no case.
Since the baker specifically refused a service due to the customers orientation, it turned into a discrimination case based on State law. Federal law does not (yet) consider sexual orientation to be a protected class, but some states have added those protections.
If Hermes, or any other U.S. Store, has an item on a shelf for purchase, and the SA does not want to sell it to an interested customer, the SA could probably say it is display only, or on hold, etc, but they cannot
state as a reason aversion to that customer based on any of the criteria of a protected class. In theorry, the laws prevent discriminatory practices, but In reality, only the most poorly trained salespeople would ever make such a statement. It is much easier to simply state "this item is not available at this time."