Both Yes and No.
It is indeed a proven fact that many homophobic males may actually be sexually attracted to males themselves, such as in the case of the 14 Anti-Gay Activists that later on was caught with their pants down with other guys.
However, this only accounts for a portion of the homophobes, not everyone. Some of them just don't like homosexuals without any legitimate reason at all, other than just being hating individuals, while others dislike them not because of their sexual orientation in itself but because of the attitude many gay people has.
Unfortunately I must asdmit that I myself has sometimes succumbed to such views aswell, because of crappy experiences with gay people, and unfortunately to an extent, still do, although I constantly try to remind myself that everyone is different and not the same even in a Community and holding a negative view towards a whole group only because of what some of them do, is highly unfair.
Sometimes, however, I have wondered if selfproclaimed transsexuals that hates transvestites(As some of them do), may be closet transvestites themselves but consider it being "finer" posing as transsexuals.
On the other hand, those aswell, could ofcourse also just had crappy experiences.
Anyway, it is true in some cases but not true in others.
It would be interesting, by the way, to see what research would give regarding homophobic females, for although they are proportionally fewer, they do indeed exist aswell.
Which, by the way, gave rise to another provoking question: Are heterophobic gay people secretly turned on by heterosexuals?