When I was in my early twenties, one of my close friends was a hippy guy around my age. He had long hair (that I was envious of - so curly) and routinely wore skirts. He was straight, and there was nothing feminine about him - he was just a hippy. (Went barefoot, too - which I thought mad in London but never mind.)
Also in the 80s, there were lots of young men who did play with the cultural trappings of femininity - makeup, dresses, etc. It was no biggie then, just marked them out as a wee bit fashionable on the cutting edge end of fashion.
Somebody asked if we'd have a problem with men wearing dresses, and, fair enough, sometimes I do, when I see men who adopt a pornified version of what they imagine women wear, such as fishnets and miniskirts, and wear them in inappropriate settings, often in places where women could never get away with dressing like that. In these cases men wearing dresses is a form of powerplay, asserting dominance, and is often involving bystanders in fetishism without those bystanders' consent. I think that is different from men wearing clothes usually marketed towards women just because they like them. (My old hippy friend didn't wear miniskirts but favoured long full maxi skirts in very workaday colours.)
Anyway, here we are, forty years after my hippy friend and his long skirts in my London suburb, and the idea of a boy wearing a dress has some people in conniptions. Let clothes be clothes. Let the kid wear what he wants. It shouldn't be a big deal.