A (himself gay) friend of mine wrote a blog post entitled "In Defence of Homophobes". I have a problem with is his post: it's not an actual defence of them, merely an argument that we should not be getting them fired from jobs (outside of politics) for their views. As it happens, I pretty much completely agree with him, but for the record, an actual defence of homophobes, one that actually attempts to defend the thing which distinguishes them from the population at large - their homophobia - instead of merely treating it as an unfortunate flaw, would look rather more like the following:
Any minority group within society which cannot interact romantically with non-members of that group places its members at a severe disadvantage. Such groups include homosexuals, most Christians, and probably a fair few other groups which I have less exposure to. In a society of 100 men and 100 women, where exactly 8 members of each sex are homosexual, each straight person has 92 potential partners whereas each homosexual has only 7. Straights are therefore able to be more selective about their chosen partner, and so their relationships are likely to be better optimised for happiness. Moreover, the assumption when meeting someone in whom you have a potential romantic interest is that they are straight, which means that in order to find a partner a homosexual will generally have to go to some specialised place. For example, this is why there are specialised nightclubs for gays - it's not that gays have systematically different tastes in music to straight people, nor is it that they are more fussy about the décor - it's to facilitate a hookup culture in which gays do not face a 90%+ chance of being rejected without any consideration.
Of course, homosexuality is not something that is chosen, so it is unfair to blame homosexual people for the position in which they find themselves. But that doesn't mean we can't try to shift people's preferences towards being more straight. If there is less talk about homosexuality, then it is at least plausible that reduced exposure to the possibility of finding someone of the same sex attractive will cause people to think less about being homosexual, act according to a "straighter" set of sexual preferences, and hopefully find more satisfying relationships as a result.
It should be noted that the argument would apply the other way if homosexuals were the majority and straights the minority. Indeed, the ideal would be for everyone to be bisexual, which would raise each person's number of potential partners in the example above from a mean of 85.2 to 199. But because a) currently the majority is straight, which provides as easy coordination point, and b) it's easier to reproduce (if not necessarily to actually raise children) within the context of a straight relationship, it just so happens that barring a major shift in favour of bisexuality, it makes sense to push towards a greater homogeneity around heterosexuality.
There are counter-arguments, of course. Given that there are significant similarities between members of the same sex which do not exist across the sexes - e.g. men supposedly having a greater appetite for sex than women, and tending to be more interested than women in things like sport and computer games - homosexual relationships could have a natural hedonic advantage over straight relationships. Without doing empirical research I really don't know which effect would be larger; the point is that an actual defence of homophobes - as opposed to an argument that they should be tolerated - would treat them as reasonable people with reasonable grounds for their beliefs and actions. Of course, no actual homophobe holds his/her position because of the reasoning I have laid out above.