Would you allow children to see a show in which a man dresses up as, say, a clown? Why would you? Men don't dress like clowns. How about 2 men dressing up as a horse? Or a Chinese New Year parade with men dressed as fire-breathing dragons? Are you going to ban the under 18s from seeing Shakespeare's "As You Like It" or "The Merchant of Venice" or "Twelfth Night?" All feature women dressing as men (and even hinting at possible romantic issues between them and other men). (See, Shakespeare knew even then that nobody would pay any attention to a mere woman. To be paid any heed as if you were worth anything required that you be a male.)
Or, on Hallowe'en, do you allow children to put on costumes and dress up as something or someone other than themselves? Why would you even permit such a thing, it's just "pretend," and we don't want our children pretending, now, do we?
Drives me crazy that children have less trouble with drag than adults do. Time the adults grew up, I think. (Or at least drop the religious mumbo-jumbo that so addles their perceptions.)