There is a big difference between the Pizza & Bakery and this dude. What this man is saying he will not serve NO gays - period. He is not being asked to partake in any gay celebration. Unlike the Pizza and Bakery who were asked to create and partake a role in a gay celebration. Like the Pizza, she stated she has no problem serving gays just that she does not want to participate in any matter because of her religious convictions. Big difference here folks. Unless there is a gay car - is there?
If someone fixes Ossama Bin Laden's car, is he supporting Bin Laden? Yes. Anything which furthers the goals of people whom are against you, supports them.
Do you believe someone should fix cars for Neo Nazis? I think it is each individual's right to decide whether or not they will assist someone who supports ideas contrary to their own.