The idea that one's opinions on gay marriage serve as a proxy for whether one is homophobic or not verges on the ridiculous.
How so?
It's actually a fairly simple concept, not supporting gay marriage doesn't automatically make someone a homophobe. I have friends who have openly gay friends, yet they themselves don't actually support gay marriage. Doesn't mean they have irrational hate towards their friends or that they fear gays but rather they just personally believe that marriage is between a man and a women.
I'm personally pro gay marriage but I don't classify everyone who disagrees as homophobic