Regarding KOS-MOS...
How exactly do you censor something that isn't even covered up properly? Her little skirt thing looks more like it would be a belt or something, as it doesn't properly cover up her leotard. No matter where you look from either below or above, you'll see her leotard. Even regarding KOS-MOS' design from Xenosaga 1.
The skirt is impractical as it doesn't properly cover her up. You can't use a blackhole to cover her up as you can already see all of her leotard from looking down. KOS-MOS could get in with some modifications with her Xenosaga 3 design, but the only outfit that would have no issues with censorship is KOS-MOS' Xenosaga 2 design and oh boy, Xenosaga 2 is not in the good books.
I don't think it would've made much of a difference, considering how frickin' popular Mai is among the SNK fandom. Like despite knowing next to nothing about King of Fighters, I remember when one of the King of Fighters games released without her and fans were
livid. Mai not appearing among the cameos and not saying anything about her would more than likely have had fans clamouring for why she wasn't in.