Actually, same logic does apply, but goes against your saying.  The example provided is all about how the cake is decorated, rather than who is buying the cake.  As long as the Homosexual baker doesn't make a cake that says "Sodomy is Evil" for anybody, then he doesn't have to sell it to everyone.  The Hobby Lobby case is a bit different from that.  This is about a cake that the baker already makes for straight couples.  The big question is can he refuse to sell this cake to gay couples because of his religious beliefs?