If the "vendors" stick to the "I don't want to make your wedding cake" and "I don't want to supply flowers for your wedding" and completely hold their tongue at that, I've really got really *ZERO PROBLEM WITH THAT*
As soon as they trot that "additional part" -- "because you are Gay/Lesbian/Black/Inuit/Chinese/1912-Baptist-Reform/Muslim" THAT is when we gots problems.
Learn to bite your tongue and you can be a closet case of Anti-something all you want. Keep your ignorance to your self.