If it is in fun and as a joke then that is OK.
Like dressing up for halloween.
If the parent takes it serious and wants the kid to dress like that other than as a joke, that is a problem IMO.
Kids are innocent until someone else takes charge and corrupts them.
Kids want to act out and pretend and that is what it looks like is going on here.
I think it is up to the parent and other adults in a childs life to guide them in the proper direction.
My grand daughters play with Bratz dolls (disgusting things), and they are young and just pretending.
When they get into the "attitude talk" I tell them that sounds silly and do they really want to look like those dolls, and I turn up my nose - and say "gross".
So far they don't want to go down that road as they still respect me and my views and because I don't like it, they don't either.
That will change, but if you try and ban stuff from their lives (toys, clothes etc.), and their friends have it, they will just use it when at their friends.