This just isn't true. On the very day the Supreme Court agreed to take up the initial case, the person involved in the complaint being taken up by the Colorado Civil Rights Commission, Autumn Scardina, asked for this specially-designed cake. A few months later, a person called and was identified through caller ID as "Scardina" and asked for a birthday cake for Satan, with an image of Satan smoking weed. A few days before that an email was sent asking for a cake dedicated to Lucifer with an upside down cross. On the exact day that Mr. Phillips won his Supreme Court case, an email requested Satan again with an image of Satan licking a sexual object. A few days later a person identifying themself as "Autumn" requested a cake with a pentagram.
I'm inclined to believe he is a target.
As far as I understand it, this is a matter of a specific product. Mr. Phillips would gladly serve a gay couple or a transgender couple, he simply didn't want to make that specific cake. So a lot of people point out the protected class argument, but I think that falls short because there would still be objection whether they were a protected class or not. If sexual orientation were not a protected class, the same people opposed to Mr. Phillips' position would still be opposed; they object on principle, not because of protected class status. In that way, protected class status is irrelevant to the argument.