Then by all means get a man to play a trans man. And presentation means everything in a movie, it makes 0 sense to get somebody who doesn't look a smidge masculine to play a trans man. Same reason why everybody was so up in arms about Christian Bale, a white man playing Moses, an Egyptian, or for that matter, Scarlett Jo, a white chick playing Motoko Kusanagi, an Asian chick in GitS.
what do you mean by masculine?
what makes a man "masculine" to you?