I would respect his opinion, not everybody in this world is going to embrace gay people with open arms and be like "Hey I love you gays". Just move on (maybe a hair flip), and ignore it if you want. Reacting to it would make you look like an ass.
i could say that i'd drag his bitch ass out to dry but honestly if i really were faced with that situation i'd be too stunned and disgusted to say anything or react. and i wouldn't even drag him or insult him. i'd get him back, but i'd do it quietly like he'd never know it was me but like i'd do something to him for sure to make him think karma's out to get him.