Homosexual military service members have been serving the United States without incident for many years. The only thing impacting their service was discrimination against them legally, with the "Don't Ask Don't Tell" policy. In addition to discharging gay service members pointless, DADT also fueled societal prejudices against homosexuals. The problem is not the homosexuals, it is those who are against them.
This debate makes little sense. War is not about sex. Although, that isn't quite true. Men used to rape other men on the opposing side to degrade them during war. But that aside, sexuality and serving your country honorably in battle are not mutually exclusive. Gays have served in the military since the beginning of time and done so at their own personal expense.