I kind of agree with shonuff, but I also can imagine some heterosexist schmuck coming in and making the gay bakers do an anti-gay cake just out of harassment towards the bakers themselves (in addition to the gay community). Like, it would drive their point home in a more severe way.
"For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring." - Carl Sagan