What are you arguing about? Eva didn't blame it solely on lack of experience. She literally said that she will not portray a trans/sisssy/gay route for Ian because
1) it's not her thing, AND
2) she lacks experience with it
There is nothing dramatic here at all. She has admitted to what you want her to admit. I would imagine that people who are trans and gay all have had a special experience; struggling with feelings of not belonging, finding who you are, coming to terms with it, being forced to face the judgement of others etcetera. Portraying that is not easy, and should probably not be done by someone who lacks the knowledge to make an accurate portrayal of it.
And while you can absolutely do enough research to do it, it again comes down to the fact that she feels it's not her thing and that it is therefore best left to others who already have that competence. You don't need to have experience with everything you write, but considering today's popular culture (books, movies, porn etcetera), it does not suprise me that someone has more experience with suger daddies, bimbos, drug dealers and incest than they do with understanding all the emotions that a trans or gay person goes through.