IMHO the real issue is would a costume like this lead to increased attacks on transwomen? I think not, I don't think transwomwn are attacked because of a costume.
But I could be wrong.
So because I would not want to add to anything like a culture of hate for trans women (and because I do not have the legs to pull it off) I would not wear it.
But I seriously resent the fact that a trans celebrity should be considered 'off limits' on a Halloween costume when other female celebrities and other 'regular' women are not off limits.
Could one argue that these types of costumes lead to increased attacks on women... www.partycity.com/category/halloween+costumes/womens+costumes+accessories.do
I initially Googled sexy costumes just to make a point but even when you do not Google sexy costumes if you Google 'halloween costimes for women' that's what you get!
Also, seriously, how can it be OK for Caitlyn to dress in this way and no one else, who knows someone may be trans and buying this costume for that reason. Surely being trans is about not policing what people can wear, or have I got that wrong!
Plus bearing in mind all the violence against trans people, gay people, straight people, males and let's not forget females I wonder why the media doesn't have more important things to complain about! 
