Well Debate.org seems to agree with what I think you are trying to say which is "being against gay marriage does not make you a homophobe"[0], of course Slate would disagree with you [1], and The Atlantic would agree with you [2]. I could go on but I won't, I'll just tell you what I think: yes, It does.

And yes, he was a homophobe, by giving to a group of people trying to destroy human rights for homosexuals. I think people can change but the complete lack of response on that specific issue from Brendan Eich makes me assume he still is.

[0] http://www.debate.org/opinions/does-opposing-same-sex-marria...

[1] http://www.slate.com/blogs/outward/2013/12/16/gay_marriage_o...

[2] http://www.theatlantic.com/national/archive/2013/12/being-ag...