Pretend you see the troon for what it is, a hideous mass of mutilated flesh grasping at a form it fetishises and idealises but cannot understand.
Say you think mtf troons are valid/hot/whatever, and the man who wants to be seen not as a mtf troon but as a woman gets INCREDIBLY Pissed.
It reminds him this is just a gross fetish and men who want men in dresses... that's the best he's gonna get. he's never going to successfully guilt the sexiest woman ever into fucking him.