Has your friend specified what reasons she was considering them as not being "genuine" corss-dressers?
Has she got some categorisation in her mind, where there is a continuum from which she includes cross-dressers.
Just like some transgendered/transgender/transexual people have strong feelings about which "T" catergory they belong to, and often look down at trans-dressers or cross-dressers. Or have strong feelings about Drag Queens.
Just like some "gay people" feel strognly about bisexuals being "nothing but cheater or deluded sihonest people". They have a reason being them, be it a good or bad reason.
Just like some Black Panthers type may have judged Obama to be too "Oreo" to claim him.
In other words, to really understand your friend before judging her, we need to know which mental universe she is operating into, which paradigms she holds dear, which separations she operates being the various "tribes" she believes exist around her.
Which discriminations she holds dear.
Which mental hierarchies she has established and who she wants to exclude from them by design; or ends-up excluding without intending to hurt them.
Then we can try and establish if she is just trying to exclude them, or to protect herself, or protect others.
She may have the best of intentions, without realizing that other people have other mental structures, other mental imagery of they fit in the world and why.
And that applies to us to, before we judge her!