A common which the Christian Right tries to make against gays and efforts to increase social acceptance of homosexuality is the idea that gays want to "recruit" others -- especially children -- into their "lifestyle." People who know gays and understand homosexuality find this position absurd, but it does seem to follow logically from the starting assumptions which the Christian Right has about homosexuality generally.
Perhaps the most important assumption which serves as a foundation for all Christian Right attitudes towards homosexuality is that it is a chosen behavior rather than an innate orientation. They define homosexuality as same-sex sexual behavior, not same-sex attraction that has emotional and psychological as well as sexual components. In this manner it is treated as a sin just like theft -- however strong the desire may be, it's something a person has control over acting on. Just as a kleptomaniac's obsessive desire to steal must be punished, so must a homosexual's desire to engage in same-sex behavior be punished.
This is what lies behind the entire notion of a person becoming "ex-gay." They may continue to experience attraction to members of the same sex, but so long as they don't act on their desires then they aren't really "gay" anymore. It's also what lies behind the belief that gays have to "recruit" others into their "lifestyle." Because attraction to members of the same sex is unnatural, then it must necessarily be created by others Christian Nationalists are especially concerned about children being recruited. They fear that anything which depicts homosexuality in an even neutral manner is part of an organized conspiracy to subvert Christian morality and Christian civilization.
Thus the suppression of non-negative depictions of homosexuality is like suppressing non-negative depictions of stealing, assault, or even murder. It's simply not a question that requires any serious ethical debate: of course children shouldn't be given the impression that such sinful behavior is even remotely acceptable. If they start believing this, then they might start engaging in this behavior themselves.
This image is based on a World War II poster encouraging soldiers to "Keep Clean" and "Take a bath every day you can." I've only changed the text -- the expressions and positions of the men are precisely as they are in the original. The homoerotic overtones are unmistakable and quite curious.