"Well, to be fair, he is beautiful and is wearing that dress infinitely better than a short, dumpy female."
Basic misogyny.
Women tend to be shorter than men, due to our biology we also tend to be curvier, sorry, dumpy.
The constant assertion that men make better women than women do is depressing. But not at all new.
With this item, no-one is saying that boys cannot wear bras, nor that they cannot buy bras from this brand. Why are so many people reacting as if that is what they had said? Is it easier to react to a perceived stance than read and understand what has actually happened? No-one wants to ban men or boys from wearing women's underwear if they choose and men and boys have been wearing women's underwear forever.
What they want to do is remove all reference to girls from a company that was set up specifically to help girls.
There have been calls to take the F out of FGM, a charity helping with menstruation issues around the world (stopping school, not having anything to help, being banished etc) has been lambasted for saying they help girls, and we have had an "educational" piece about sex in a magazine aimed primarily at teenage girls, calling them "non prostate havers", omitting any mention of the clitoris and exhorting them to try anal sex.
I have not seen ANY similar attacks on things specific to men or boys apart from one TM upset that gay men wouldn't consider them as a sexual partner, and would be very interested to see if anyone else has.
This all points to misogyny - it's absolutely basically obvious.