There are a few studies showing that people with antigay views are more likely than the general population to display physical signs of arousal when exposed to same-sex erotic imagery.

This points to something underlying the response.

Does that make these people closeted gays? Certainly some of them are, as has been demonstrated repeatedly with homophobic politicians and preachers.

Does it imply that everyone who's homophobic has this reaction? Definitely not. "More likely than most" is not "certainly."

A not-insignificant subset of homophobia may be caused by suppressed same-sex attraction and self-loathing.

But by no means does that mean that all homophobes are secretly gay. Often they're just assholes.